Patent Publication Number: US-2023133887-A1

Title: Generating an analog drive sense signal

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present U.S. Utility Patent Application claims priority pursuant to 35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No. 17/815,044, entitled “ANALOG DRIVE SENSE CIRCUIT,” filed Jul. 26, 2022, which is a continuation of U.S. Utility application Ser. No. 17/317,734, entitled “ANALOG-DIGITAL DRIVE SENSE CIRCUIT,” filed May 11, 2021, issued as U.S. Pat. No. 11,429,226 on Aug. 30, 2022, which is a continuation-in-part of U.S. Utility application Ser. No. 16/113,379, entitled “DRIVE SENSE CIRCUIT WITH DRIVE-SENSE LINE,” filed Aug. 27, 2018, issued as U.S. Pat. No. 11,099,032 on Aug. 24, 2021, all of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility Patent Application for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     Technical Field of the Invention 
     This invention relates generally to data communication systems and more particularly to sensed data collection and/or communication. 
     Description of Related Art 
     Sensors are used in a wide variety of applications ranging from in-home automation, to industrial systems, to health care, to transportation, and so on. For example, sensors are placed in bodies, automobiles, airplanes, boats, ships, trucks, motorcycles, cell phones, televisions, touch-screens, industrial plants, appliances, motors, checkout counters, etc. for the variety of applications. 
     In general, a sensor converts a physical quantity into an electrical or optical signal. For example, a sensor converts a physical phenomenon, such as a biological condition, a chemical condition, an electric condition, an electromagnetic condition, a temperature, a magnetic condition, mechanical motion (position, velocity, acceleration, force, pressure), an optical condition, and/or a radioactivity condition, into an electrical signal. 
     A sensor includes a transducer, which functions to convert one form of energy (e.g., force) into another form of energy (e.g., electrical signal). There are a variety of transducers to support the various applications of sensors. For example, a transducer is capacitor, a piezoelectric transducer, a piezoresistive transducer, a thermal transducer, a thermal-couple, a photoconductive transducer such as a photoresistor, a photodiode, and/or phototransistor. 
     A sensor circuit is coupled to a sensor to provide the sensor with power and to receive the signal representing the physical phenomenon from the sensor. The sensor circuit includes at least three electrical connections to the sensor: one for a power supply; another for a common voltage reference (e.g., ground); and a third for receiving the signal representing the physical phenomenon. The signal representing the physical phenomenon will vary from the power supply voltage to ground as the physical phenomenon changes from one extreme to another (for the range of sensing the physical phenomenon). 
     The sensor circuits provide the received sensor signals to one or more computing devices for processing. A computing device is known to communicate data, process data, and/or store data. The computing device may be a cellular phone, a laptop, a tablet, a personal computer (PC), a work station, a video game device, a server, and/or a data center that support millions of web searches, stock trades, or on-line purchases every hour. 
     The computing device processes the sensor signals for a variety of applications. For example, the computing device processes sensor signals to determine temperatures of a variety of items in a refrigerated truck during transit. As another example, the computing device processes the sensor signals to determine a touch on a touch screen. As yet another example, the computing device processes the sensor signals to determine various data points in a production line of a product. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG.  1    is a schematic block diagram of an embodiment of a communication system; 
         FIG.  2    is a schematic block diagram of an embodiment of a computing device; 
         FIG.  3    is a schematic block diagram of another embodiment of a computing device; 
         FIG.  4    is a schematic block diagram of another embodiment of a computing device; 
         FIG.  5 A  is a schematic plot diagram of a computing subsystem; 
         FIG.  5 B  is a schematic block diagram of another embodiment of a computing subsystem; 
         FIG.  5 C  is a schematic block diagram of another embodiment of a computing subsystem; 
         FIG.  5 D  is a schematic block diagram of another embodiment of a computing subsystem; 
         FIG.  5 E  is a schematic block diagram of another embodiment of a computing subsystem; 
         FIG.  6    is a schematic block diagram of an embodiment of a drive sense circuit; 
         FIG.  6 A  is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  7    is an example of a power signal graph; 
         FIG.  8    is an example of a sensor graph; 
         FIG.  9    is a schematic block diagram of another example of a power signal graph; 
         FIG.  10    is a schematic block diagram of another example of a power signal graph; 
         FIG.  11    is a schematic block diagram of another example of a power signal graph; 
         FIG.  11 A  is a schematic block diagram of another example of a power signal graph; 
         FIG.  12    is a schematic block diagram of an embodiment of a power signal change detection circuit; 
         FIG.  13    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  14    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  15    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  16    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  17    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  18    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  19    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  20    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  21    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  22    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  23    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  24    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  24 A  is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  24 B  is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  25    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  26    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  26 A  is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  27    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  28    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  29    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  30    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  30 A  is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  31    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  32    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  33    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  34    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  35    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  36    is a schematic block diagram of another embodiment of a drive sense circuit; 
         FIG.  37    is a schematic block diagram of another embodiment of a drive sense circuit; and 
         FIG.  38    is a schematic block diagram of another embodiment of a drive sense circuit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG.  1    is a schematic block diagram of an embodiment of a communication system  10  that includes a plurality of computing. devices  12 - 10 , one or more servers  22 , one or more databases  24 , one or more networks  26 , a plurality of drive-sense circuits  28 , a plurality of sensors  30 , and a plurality of actuators  32 . Computing devices  14  include a touch screen  16  with sensors and drive-sensor circuits and computing devices  18  include a touch &amp; tactic screen  20  that includes sensors, actuators, and drive-sense circuits. 
     A sensor  30  functions to convert a physical input into an electrical output and/or an optical output. The physical input of a sensor may be one of a variety of physical input conditions. For example, the physical condition includes one or more of, but is not limited to, acoustic waves (e.g., amplitude, phase, polarization, spectrum, and/or wave velocity); a biological and/or chemical condition (e.g., fluid concentration, level, composition, etc.); an electric condition (e.g., charge, voltage, current, conductivity, permittivity, eclectic field, which includes amplitude, phase, and/or polarization); a magnetic condition (e.g., flux, permeability, magnetic field, which amplitude, phase, and/or polarization); an optical condition (e.g., refractive index, reflectivity, absorption, etc.); a thermal condition (e.g., temperature, flux, specific heat, thermal conductivity, etc.); and a mechanical condition (e.g., position, velocity, acceleration, force, strain, stress, pressure, torque, etc.). For example, piezoelectric sensor converts force or pressure into an eclectic signal. As another example, a microphone converts audible acoustic waves into electrical signals. 
     There are a variety of types of sensors to sense the various types of physical conditions. Sensor types include, but are not limited to, capacitor sensors, inductive sensors, accelerometers, piezoelectric sensors, light sensors, magnetic field sensors, ultrasonic sensors, temperature sensors, infrared (IR) sensors, touch sensors, proximity sensors, pressure sensors, level sensors, smoke sensors, and gas sensors. In many ways, sensors function as the interface between the physical world and the digital world by converting real world conditions into digital signals that are then processed by computing devices for a vast number of applications including, but not limited to, medical applications, production automation applications, home environment control, public safety, and so on. 
     The various types of sensors have a variety of sensor characteristics that are factors in providing power to the sensors, receiving signals from the sensors, and/or interpreting the signals from the sensors. The sensor characteristics include resistance, reactance, power requirements, sensitivity, range, stability, repeatability, linearity, error, response time, and/or frequency response. For example, the resistance, reactance, and/or power requirements are factors in determining drive circuit requirements. As another example, sensitivity, stability, and/or linear are factors for interpreting the measure of the physical condition based on the received electrical and/or optical signal (e.g., measure of temperature, pressure, etc.). 
     An actuator  32  converts an electrical input into a physical output. The physical output of an actuator may be one of a variety of physical output conditions. For example, the physical output condition includes one or more of, but is not limited to, acoustic waves (e.g., amplitude, phase, polarization, spectrum, and/or wave velocity); a magnetic condition (e.g., flux, permeability, magnetic field, which amplitude, phase, and/or polarization); a thermal condition (e.g., temperature, flux, specific heat, thermal conductivity, etc.); and a mechanical condition (e.g., position, velocity, acceleration, force, strain, stress, pressure, torque, etc.). As an example, a piezoelectric actuator converts voltage into force or pressure. As another example, a speaker converts electrical signals into audible acoustic waves. 
     An actuator  32  may be one of a variety of actuators. For example, an actuator  32  is one of a comb drive, a digital micro-mirror device, an electric motor, an electroactive polymer, a hydraulic cylinder, a piezoelectric actuator, a pneumatic actuator, a screw jack, a servomechanism, a solenoid, a stepper motor, a shape-memory allow, a thermal bimorph, and a hydraulic actuator. 
     The various types of actuators have a variety of actuators characteristics that are factors in providing power to the actuator and sending signals to the actuators for desired performance. The actuator characteristics include resistance, reactance, power requirements, sensitivity, range, stability, repeatability, linearity, error, response time, and/or frequency response. For example, the resistance, reactance, and power requirements are factors in determining drive circuit requirements. As another example, sensitivity, stability, and/or linear are factors for generating the signaling to send to the actuator to obtain the desired physical output condition. 
     The computing devices  12 ,  14 , and  18  may each be a portable computing device and/or a fixed computing device. A portable computing device may be a social networking device, a gaming device, a cell phone, a smart phone, a digital assistant, a digital music player, a digital video player, a laptop computer, a handheld computer, a tablet, a video game controller, and/or any other portable device that includes a computing core. A fixed computing device may be a computer (PC), a computer server, a cable set-top box, a satellite receiver, a television set, a printer, a fax machine, home entertainment equipment, a video game console, and/or any type of home or office computing equipment. The computing devices  12 ,  14 , and  18  will be discussed in greater detail with reference to one or more of  FIGS.  2 - 4   . 
     A server  22  is a special type of computing device that is optimized for processing large amounts of data requests in parallel. A server  22  includes similar components to that of the computing devices  12 ,  14 , and/or  18  with more robust processing modules, more main memory, and/or more hard drive memory (e.g., solid state, hard drives, etc.). Further, a server  22  is typically accessed remotely; as such it does not generally include user input devices and/or user output devices. In addition, a server may be a standalone separate computing device and/or may be a cloud computing device. 
     A database  24  is a special type of computing device that is optimized for large scale data storage and retrieval. A database  24  includes similar components to that of the computing devices  12 ,  14 , and/or  18  with more hard drive memory (e.g., solid state, hard drives, etc.) and potentially with more processing modules and/or main memory. Further, a database  24  is typically accessed remotely; as such it does not generally include user input devices and/or user output devices. In addition, a database  24  may be a standalone separate computing device and/or may be a cloud computing device. 
     The network  26  includes one more local area networks (LAN) and/or one or more wide area networks WAN), which may be a public network and/or a private network. A LAN may be a wireless-LAN (e.g., Wi-Fi access point, Bluetooth, ZigBee, etc.) and/or a wired network (e.g., Firewire, Ethernet, etc.). A WAN may be a wired and/or wireless WAN. For example, a LAN may be a personal home or business&#39;s wireless network and a WAN is the Internet, cellular telephone infrastructure, and/or satellite communication infrastructure. 
     In an example of operation, computing device  12 - 1  communicates with a plurality of drive-sense circuits  28 , which, in turn, communicate with a plurality of sensors  30 . The sensors  30  and/or the drive-sense circuits  28  are within the computing device  12 - 1  and/or external to it. For example, the sensors  30  may be external to the computing device  12 - 1  and the drive-sense circuits are within the computing device  12 - 1 . As another example, both the sensors  30  and the drive-sense circuits  28  are external to the computing device  12 - 1 . When the drive-sense circuits  28  are external to the computing device, they are coupled to the computing device  12 - 1  via wired and/or wireless communication links as will be discussed in greater detail with reference to one or more of  FIGS.  5 A- 5 C . 
     The computing device  12 - 1  communicates with the drive-sense circuits  28  to; (a) turn them on, (b) obtain data from the sensors (individually and/or collectively), (c) instruct the drive sense circuit on how to communicate the sensed data to the computing device  12 - 1 , (d) provide signaling attributes (e.g., DC level, AC level, frequency, power level, regulated current signal, regulated voltage signal, regulation of an impedance, frequency patterns for various sensors, different frequencies for different sensing applications, etc.) to use with the sensors, and/or (e) provide other commands and/or instructions. 
     As a specific example, the sensors  30  are distributed along a pipeline to measure flow rate and/or pressure within a section of the pipeline. The drive-sense circuits  28  have their own power source (e.g., battery, power supply, etc.) and are proximally located to their respective sensors  30 . At desired time intervals (milliseconds, seconds, minutes, hours, etc.), the drive-sense circuits  28  provide a regulated source signal or a power signal to the sensors  30 . An electrical characteristic of the sensor  30  affects the regulated source signal or power signal, which is reflective of the condition (e.g., the flow rate and/or the pressure) that sensor is sensing. 
     The drive-sense circuits  28  detect the effects on the regulated source signal or power signals as a result of the electrical characteristics of the sensors. The drive-sense circuits  28  then generate signals representative of change to the regulated source signal or power signal based on the detected effects on the power signals. The changes to the regulated source signals or power signals are representative of the conditions being sensed by the sensors  30 . 
     The drive-sense circuits  28  provide the representative signals of the conditions to the computing device  12 - 1 . A representative signal may be an analog signal or a digital signal. In either case, the computing device  12 - 1  interprets the representative signals to determine the pressure and/or flow rate at each sensor location along the pipeline. The computing device may then provide this information to the server  22 , the database  24 , and/or to another computing device for storing and/or further processing. 
     As another example of operation, computing device  12 - 2  is coupled to a drive-sense circuit  28 , which is, in turn, coupled to a senor  30 . The sensor  30  and/or the drive-sense circuit  28  may be internal and/or external to the computing device  12 - 2 . In this example, the sensor  30  is sensing a condition that is particular to the computing device  12 - 2 . For example, the sensor  30  may be a temperature sensor, an ambient light sensor, an ambient noise sensor, etc. As described above, when instructed by the computing device  12 - 2  (which may be a default setting for continuous sensing or at regular intervals), the drive-sense circuit  28  provides the regulated source signal or power signal to the sensor  30  and detects an effect to the regulated source signal or power signal based on an electrical characteristic of the sensor. The drive-sense circuit generates a representative signal of the affect and sends it to the computing device  12 - 2 . 
     In another example of operation, computing device  12 - 3  is coupled to a plurality of drive-sense circuits  28  that are coupled to a plurality of sensors  30  and is coupled to a plurality of drive-sense circuits  28  that are coupled to a plurality of actuators  32 . The generally functionality of the drive-sense circuits  28  coupled to the sensors  30  in accordance with the above description. 
     Since an actuator  32  is essentially an inverse of a sensor in that an actuator converts an electrical signal into a physical condition, while a sensor converts a physical condition into an electrical signal, the drive-sense circuits  28  can be used to power actuators  32 . Thus, in this example, the computing device  12 - 3  provides actuation signals to the drive-sense circuits  28  for the actuators  32 . The drive-sense circuits modulate the actuation signals on to power signals or regulated control signals, which are provided to the actuators  32 . The actuators  32  are powered from the power signals or regulated control signals and produce the desired physical condition from the modulated actuation signals. 
     As another example of operation, computing device  12 - x  is coupled to a drive-sense circuit  28  that is coupled to a sensor  30  and is coupled to a drive-sense circuit  28  that is coupled to an actuator  32 . In this example, the sensor  30  and the actuator  32  are for use by the computing device  12 - x . For example, the sensor  30  may be a piezoelectric microphone and the actuator  32  may be a piezoelectric speaker. 
       FIG.  2    is a schematic block diagram of an embodiment of a computing device  12  (e.g., any one of  12 - 1  through  12 - x ). The computing device  12  includes a core control module  40 , one or more processing modules  42 , one or more main memories  44 , cache memory  46 , a video graphics processing module  48 , a display  50 , an Input-Output (I/O) peripheral control module  52 , one or more input interface modules  56 , one or more output interface modules  58 , one or more network interface modules  60 , and one or more memory interface modules  62 . A processing module  42  is described in greater detail at the end of the detailed description of the invention section and, in an alternative embodiment, has a direction connection to the main memory  44 . In an alternate embodiment, the core control module  40  and the I/O and/or peripheral control module  52  are one module, such as a chipset, a quick path interconnect (QPI), and/or an ultra-path interconnect (UPI). 
     Each of the main memories  44  includes one or more Random Access Memory (RAM) integrated circuits, or chips. For example, a main memory  44  includes four DDR4 (4 th  generation of double data rate) RAM chips, each running at a rate of 2,400 MHz. In general, the main memory  44  stores data and operational instructions most relevant for the processing module  42 . For example, the core control module  40  coordinates the transfer of data and/or operational instructions from the main memory  44  and the memory  64 - 66 . The data and/or operational instructions retrieve from memory  64 - 66  are the data and/or operational instructions requested by the processing module or will most likely be needed by the processing module. When the processing module is done with the data and/or operational instructions in main memory, the core control module  40  coordinates sending updated data to the memory  64 - 66  for storage. 
     The memory  64 - 66  includes one or more hard drives, one or more solid state memory chips, and/or one or more other large capacity storage devices that, in comparison to cache memory and main memory devices, is/are relatively inexpensive with respect to cost per amount of data stored. The memory  64 - 66  is coupled to the core control module  40  via the I/O and/or peripheral control module  52  and via one or more memory interface modules  62 . In an embodiment, the I/O and/or peripheral control module  52  includes one or more Peripheral Component Interface (PCI) buses to which peripheral components connect to the core control module  40 . A memory interface module  62  includes a software driver and a hardware connector for coupling a memory device to the I/O and/or peripheral control module  52 . For example, a memory interface  62  is in accordance with a Serial Advanced Technology Attachment (SATA) port. 
     The core control module  40  coordinates data communications between the processing module(s)  42  and the network(s)  26  via the I/O and/or peripheral control module  52 , the network interface module(s)  60 , and a network card  68  or  70 . A network card  68  or  70  includes a wireless communication unit or a wired communication unit. A wireless communication unit includes a wireless local area network (WLAN) communication device, a cellular communication device, a Bluetooth device, and/or a ZigBee communication device. A wired communication unit includes a Gigabit LAN connection, a Firewire connection, and/or a proprietary computer wired connection. A network interface module  60  includes a software driver and a hardware connector for coupling the network card to the I/O and/or peripheral control module  52 . For example, the network interface module  60  is in accordance with one or more versions of IEEE 802.11, cellular telephone protocols, 10/100/1000 Gigabit LAN protocols, etc. 
     The core control module  40  coordinates data communications between the processing module(s)  42  and input device(s)  72  via the input interface module(s)  56  and the I/O and/or peripheral control module  52 . An input device  72  includes a keypad, a keyboard, control switches, a touchpad, a microphone, a camera, etc. An input interface module  56  includes a software driver and a hardware connector for coupling an input device to the I/O and/or peripheral control module  52 . In an embodiment, an input interface module  56  is in accordance with one or more Universal Serial Bus (USB) protocols. 
     The core control module  40  coordinates data communications between the processing module(s)  42  and output device(s)  74  via the output interface module(s)  58  and the I/O and/or peripheral control module  52 . An output device  74  includes a speaker, etc. An output interface module  58  includes a software driver and a hardware connector for coupling an output device to the I/O and/or peripheral control module  52 . In an embodiment, an output interface module  56  is in accordance with one or more audio codec protocols. 
     The processing module  42  communicates directly with a video graphics processing module  48  to display data on the display  50 . The display  50  includes an LED (light emitting diode) display, an LCD (liquid crystal display), and/or other type of display technology. The display has a resolution, an aspect ratio, and other features that affect the quality of the display. The video graphics processing module  48  receives data from the processing module  42 , processes the data to produce rendered data in accordance with the characteristics of the display, and provides the rendered data to the display  50 . 
       FIG.  2    further illustrates sensors  30  and actuators  32  coupled to drive-sense circuits  28 , which are coupled to the input interface module  56  (e.g., USB port). Alternatively, one or more of the drive-sense circuits  28  is coupled to the computing device via a wireless network card (e.g., WLAN) or a wired network card (e.g., Gigabit LAN). While not shown, the computing device  12  further includes a BIOS (Basic Input Output System) memory coupled to the core control module  40 . 
       FIG.  3    is a schematic block diagram of another embodiment of a computing device  14  that includes a core control module  40 , one or more processing modules  42 , one or more main memories  44 , cache memory  46 , a video graphics processing module  48 , a touch screen  16 , an Input-Output (I/O) peripheral control module  52 , one or more input interface modules  56 , one or more output interface modules  58 , one or more network interface modules  60 , and one or more memory interface modules  62 . The touch screen  16  includes a touch screen display  80 , a plurality of sensors  30 , a plurality of drive-sense circuits (DSC), and a touch screen processing module  82 . 
     Computing device  14  operates similarly to computing device  12  of  FIG.  2    with the addition of a touch screen as an input device. The touch screen includes a plurality of sensors (e.g., electrodes, capacitor sensing cells, capacitor sensors, inductive sensor, etc.) to detect a proximal touch of the screen. For example, when one or more fingers touches the screen, capacitance of sensors proximal to the touch(es) are affected (e.g., impedance changes). The drive-sense circuits (DSC) coupled to the affected sensors detect the change and provide a representation of the change to the touch screen processing module  82 , which may be a separate processing module or integrated into the processing module  42 . 
     The touch screen processing module  82  processes the representative signals from the drive-sense circuits (DSC) to determine the location of the touch(es). This information is inputted to the processing module  42  for processing as an input. For example, a touch represents a selection of a button on screen, a scroll function, a zoom in-out function, etc. 
       FIG.  4    is a schematic block diagram of another embodiment of a computing device  18  that includes a core control module  40 , one or more processing modules  42 , one or more main memories  44 , cache memory  46 , a video graphics processing module  48 , a touch and tactile screen  20 , an Input-Output (I/O) peripheral control module  52 , one or more input interface modules  56 , one or more output interface modules  58 , one or more network interface modules  60 , and one or more memory interface modules  62 . The touch and tactile screen  20  includes a touch and tactile screen display  90 , a plurality of sensors  30 , a plurality of actuators  32 , a plurality of drive-sense circuits (DSC), a touch screen processing module  82 , and a tactile screen processing module  92 . 
     Computing device  18  operates similarly to computing device  14  of  FIG.  3    with the addition of a tactile aspect to the screen  20  as an output device. The tactile portion of the screen  20  includes the plurality of actuators (e.g., piezoelectric transducers to create vibrations, solenoids to create movement, etc.) to provide a tactile feel to the screen  20 . To do so, the processing module creates tactile data, which is provided to the appropriate drive-sense circuits (DSC) via the tactile screen processing module  92 , which may be a stand-alone processing module or integrated into processing module  42 . The drive-sense circuits (DSC) convert the tactile data into drive-actuate signals and provide them to the appropriate actuators to create the desired tactile feel on the screen  20 . 
       FIG.  5 A  is a schematic plot diagram of a computing subsystem  25  that includes a sensed data processing module  65 , a plurality of communication modules  61 A- x , a plurality of processing modules  42 A- x , a plurality of drive sense circuits  28 , and a plurality of sensors  1 - x , which may be sensors  30  of  FIG.  1   . The sensed data processing module  65  is one or more processing modules within one or more servers  22  and/or one more processing modules in one or more computing devices that are different than the computing devices in which processing modules  42 A- x  reside. 
     A drive-sense circuit  28  (or multiple drive-sense circuits), a processing module (e.g.,  41 A), and a communication module (e.g.,  61 A) are within a common computing device. Each grouping of a drive-sense circuit(s), processing module, and communication module is in a separate computing device. A communication module  61 A- x  is constructed in accordance with one or more wired communication protocol and/or one or more wireless communication protocols that is/are in accordance with the one or more of the Open System Interconnection (OSI) model, the Transmission Control Protocol/Internet Protocol (TCP/IP) model, and other communication protocol module. 
     In an example of operation, a processing module (e.g.,  42 A) provides a control signal to its corresponding drive-sense circuit  28 . The processing module  42 A may generate the control signal, receive it from the sensed data processing module  65 , or receive an indication from the sensed data processing module  65  to generate the control signal. The control signal enables the drive-sense circuit  28  to provide a drive signal to its corresponding sensor. The control signal may further include a reference signal having one or more frequency components to facilitate creation of the drive signal and/or interpreting a sensed signal received from the sensor. 
     Based on the control signal, the drive-sense circuit  28  provides the drive signal to its corresponding sensor (e.g., 1) on a drive &amp; sense line. While receiving the drive signal (e.g., a power signal, a regulated source signal, etc.), the sensor senses a physical condition  1 - x  (e.g., acoustic waves, a biological condition, a chemical condition, an electric condition, a magnetic condition, an optical condition, a thermal condition, and/or a mechanical condition). As a result of the physical condition, an electrical characteristic (e.g., impedance, voltage, current, capacitance, inductance, resistance, reactance, etc.) of the sensor changes, which affects the drive signal. Note that if the sensor is an optical sensor, it converts a sensed optical condition into an electrical characteristic. 
     The drive-sense circuit  28  detects the effect on the drive signal via the drive &amp; sense line and processes the affect to produce a signal representative of power change, which may be an analog or digital signal. The processing module  42 A receives the signal representative of power change, interprets it, and generates a value representing the sensed physical condition. For example, if the sensor is sensing pressure, the value representing the sensed physical condition is a measure of pressure (e.g., × PSI (pounds per square inch)). 
     In accordance with a sensed data process function (e.g., algorithm, application, etc.), the sensed data processing module  65  gathers the values representing the sensed physical conditions from the processing modules. Since the sensors  1 - x  may be the same type of sensor (e.g., a pressure sensor), may each be different sensors, or a combination thereof; the sensed physical conditions may be the same, may each be different, or a combination thereof. The sensed data processing module  65  processes the gathered values to produce one or more desired results. For example, if the computing subsystem  25  is monitoring pressure along a pipeline, the processing of the gathered values indicates that the pressures are all within normal limits or that one or more of the sensed pressures is not within normal limits. 
     As another example, if the computing subsystem  25  is used in a manufacturing facility, the sensors are sensing a variety of physical conditions, such as acoustic waves (e.g., for sound proofing, sound generation, ultrasound monitoring, etc.), a biological condition (e.g., a bacterial contamination, etc.) a chemical condition (e.g., composition, gas concentration, etc.), an electric condition (e.g., current levels, voltage levels, electro-magnetic interference, etc.), a magnetic condition (e.g., induced current, magnetic field strength, magnetic field orientation, etc.), an optical condition (e.g., ambient light, infrared, etc.), a thermal condition (e.g., temperature, etc.), and/or a mechanical condition (e.g., physical position, force, pressure, acceleration, etc.). 
     The computing subsystem  25  may further include one or more actuators in place of one or more of the sensors and/or in addition to the sensors. When the computing subsystem  25  includes an actuator, the corresponding processing module provides an actuation control signal to the corresponding drive-sense circuit  28 . The actuation control signal enables the drive-sense circuit  28  to provide a drive signal to the actuator via a drive &amp; actuate line (e.g., similar to the drive &amp; sense line, but for the actuator). The drive signal includes one or more frequency components and/or amplitude components to facilitate a desired actuation of the actuator. 
     In addition, the computing subsystem  25  may include an actuator and sensor working in concert. For example, the sensor is sensing the physical condition of the actuator. In this example, a drive-sense circuit provides a drive signal to the actuator and another drive sense signal provides the same drive signal, or a scaled version of it, to the sensor. This allows the sensor to provide near immediate and continuous sensing of the actuator&#39;s physical condition. This further allows for the sensor to operate at a first frequency and the actuator to operate at a second frequency. 
     In an embodiment, the computing subsystem is a stand-alone system for a wide variety of applications (e.g., manufacturing, pipelines, testing, monitoring, security, etc.). In another embodiment, the computing subsystem  25  is one subsystem of a plurality of subsystems forming a larger system. For example, different subsystems are employed based on geographic location. As a specific example, the computing subsystem  25  is deployed in one section of a factory and another computing subsystem is deployed in another part of the factory. As another example, different subsystems are employed based function of the subsystems. As a specific example, one subsystem monitors a city&#39;s traffic light operation and another subsystem monitors the city&#39;s sewage treatment plants. 
     Regardless of the use and/or deployment of the computing system, the physical conditions it is sensing, and/or the physical conditions it is actuating, each sensor and each actuator (if included) is driven and sensed by a single line as opposed to separate drive and sense lines. This provides many advantages including, but not limited to, lower power requirements, better ability to drive high impedance sensors, lower line to line interference, and/or concurrent sensing functions. 
       FIG.  5 B  is a schematic block diagram of another embodiment of a computing subsystem  25  that includes a sensed data processing module  65 , a communication module  61 , a plurality of processing modules  42 A- x , a plurality of drive sense circuits  28 , and a plurality of sensors  1 - x , which may be sensors  30  of  FIG.  1   . The sensed data processing module  65  is one or more processing modules within one or more servers  22  and/or one more processing modules in one or more computing devices that are different than the computing device, devices, in which processing modules  42 A- x  reside. 
     In an embodiment, the drive-sense circuits  28 , the processing modules, and the communication module are within a common computing device. For example, the computing device includes a central processing unit that includes a plurality of processing modules. The functionality and operation of the sensed data processing module  65 , the communication module  61 , the processing modules  42 A- x , the drive sense circuits  28 , and the sensors  1 - x  are as discussed with reference to  FIG.  5 A . 
       FIG.  5 C  is a schematic block diagram of another embodiment of a computing subsystem  25  that includes a sensed data processing module  65 , a communication module  61 , a processing module  42 , a plurality of drive sense circuits  28 , and a plurality of sensors  1 - x , which may be sensors  30  of  FIG.  1   . The sensed data processing module  65  is one or more processing modules within one or more servers  22  and/or one more processing modules in one or more computing devices that are different than the computing device in which the processing module  42  resides. 
     In an embodiment, the drive-sense circuits  28 , the processing module, and the communication module are within a common computing device. The functionality and operation of the sensed data processing module  65 , the communication module  61 , the processing module  42 , the drive sense circuits  28 , and the sensors  1 - x  are as discussed with reference to  FIG.  5 A . 
       FIG.  5 D  is a schematic block diagram of another embodiment of a computing subsystem  25  that includes a processing module  42 , a reference signal circuit  100 , a plurality of drive sense circuits  28 , and a plurality of sensors  30 . The processing module  42  includes a drive-sense processing block  104 , a drive-sense control block  102 , and a reference control block  106 . Each block  102 - 106  of the processing module  42  may be implemented via separate modules of the processing module, may be a combination of software and hardware within the processing module, and/or may be field programmable modules within the processing module  42 . 
     In an example of operation, the drive-sense control block  104  generates one or more control signals to activate one or more of the drive-sense circuits  28 . For example, the drive-sense control block  102  generates a control signal that enables of the drive-sense circuits  28  for a given period of time (e.g., 1 second, 1 minute, etc.). As another example, the drive-sense control block  102  generates control signals to sequentially enable the drive-sense circuits  28 . As yet another example, the drive-sense control block  102  generates a series of control signals to periodically enable the drive-sense circuits  28  (e.g., enabled once every second, every minute, every hour, etc.). 
     Continuing with the example of operation, the reference control block  106  generates a reference control signal that it provides to the reference signal circuit  100 . The reference signal circuit  100  generates, in accordance with the control signal, one or more reference signals for the drive-sense circuits  28 . For example, the control signal is an enable signal, which, in response, the reference signal circuit  100  generates a pre-programmed reference signal that it provides to the drive-sense circuits  28 . In another example, the reference signal circuit  100  generates a unique reference signal for each of the drive-sense circuits  28 . In yet another example, the reference signal circuit  100  generates a first unique reference signal for each of the drive-sense circuits  28  in a first group and generates a second unique reference signal for each of the drive-sense circuits  28  in a second group. 
     The reference signal circuit  100  may be implemented in a variety of ways. For example, the reference signal circuit  100  includes a DC (direct current) voltage generator, an AC voltage generator, and a voltage combining circuit. The DC voltage generator generates a DC voltage at a first level and the AC voltage generator generates an AC voltage at a second level, which is less than or equal to the first level. The voltage combining circuit combines the DC and AC voltages to produce the reference signal. As examples, the reference signal circuit  100  generates a reference signal similar to the signals shown in  FIG.  7   , which will be subsequently discussed. 
     As another example, the reference signal circuit  100  includes a DC current generator, an AC current generator, and a current combining circuit. The DC current generator generates a DC current a first current level and the AC current generator generates an AC current at a second current level, which is less than or equal to the first current level. The current combining circuit combines the DC and AC currents to produce the reference signal. 
     Returning to the example of operation, the reference signal circuit  100  provides the reference signal, or signals, to the drive-sense circuits  28 . When a drive-sense circuit  28  is enabled via a control signal from the drive sense control block  102 , it provides a drive signal to its corresponding sensor  30 . As a result of a physical condition, an electrical characteristic of the sensor is changed, which affects the drive signal. Based on the detected effect on the drive signal and the reference signal, the drive-sense circuit  28  generates a signal representative of the effect on the drive signal. 
     The drive-sense circuit provides the signal representative of the effect on the drive signal to the drive-sense processing block  104 . The drive-sense processing block  104  processes the representative signal to produce a sensed value  97  of the physical condition (e.g., a digital value that represents a specific temperature, a specific pressure level, etc.). The processing module  42  provides the sensed value  97  to another application running on the computing device, to another computing device, and/or to a server  22 . 
       FIG.  5 E  is a schematic block diagram of another embodiment of a computing subsystem  25  that includes a processing module  42 , a plurality of drive sense circuits  28 , and a plurality of sensors  30 . This embodiment is similar to the embodiment of  FIG.  5 D  with the functionality of the drive-sense processing block  104 , a drive-sense control block  102 , and a reference control block  106  shown in greater detail. For instance, the drive-sense control block  102  includes individual enable/disable blocks  102 - 1  through  102 - y . An enable/disable block functions to enable or disable a corresponding drive-sense circuit in a manner as discussed above with reference to  FIG.  5 D . 
     The drive-sense processing block  104  includes variance determining modules  104 - 1   a  through y and variance interpreting modules  104 - 2   a  through y. For example, variance determining module  104 - 1   a  receives, from the corresponding drive-sense circuit  28 , a signal representative of a physical condition sensed by a sensor. The variance determining module  104 - 1   a  functions to determine a difference from the signal representing the sensed physical condition with a signal representing a known, or reference, physical condition. The variance interpreting module  104 - 1   b  interprets the difference to determine a specific value for the sensed physical condition. 
     As a specific example, the variance determining module  104 - 1   a  receives a digital signal of 1001 0110 (150 in decimal) that is representative of a sensed physical condition (e.g., temperature) sensed by a sensor from the corresponding drive-sense circuit  28 . With 8-bits, there are 2 8  (256) possible signals representing the sensed physical condition. Assume that the units for temperature is Celsius and a digital value of 0100 0000 (64 in decimal) represents the known value for 25 degree Celsius. The variance determining module  104 - b   1  determines the difference between the digital signal representing the sensed value (e.g., 1001 0110, 150 in decimal) and the known signal value of (e.g., 0100 0000, 64 in decimal), which is 0011 0000 (86 in decimal). The variance determining module  104 - b   1  then determines the sensed value based on the difference and the known value. In this example, the sensed value equals 25+86*(100/256)=25+33.6=58.6 degrees Celsius. 
       FIG.  6    is a schematic block diagram of a drive center circuit  28 - a  coupled to a sensor  30 . The drive sense-sense circuit  28  includes a power source circuit  110  and a power signal change detection circuit  112 . The sensor  30  includes one or more transducers that have varying electrical characteristics (e.g., capacitance, inductance, impedance, current, voltage, etc.) based on varying physical conditions  114  (e.g., pressure, temperature, biological, chemical, etc.), or vice versa (e.g., an actuator). 
     The power source circuit  110  is operably coupled to the sensor  30  and, when enabled (e.g., from a control signal from the processing module  42 , power is applied, a switch is closed, a reference signal is received, etc.) provides a power signal  116  to the sensor  30 . The power source circuit  110  may be a voltage supply circuit (e.g., a battery, a linear regulator, an unregulated DC-to-DC converter, etc.) to produce a voltage-based power signal, a current supply circuit (e.g., a current source circuit, a current mirror circuit, etc.) to produce a current-based power signal, or a circuit that provide a desired power level to the sensor and substantially matches impedance of the sensor. The power source circuit  110  generates the power signal  116  to include a DC (direct current) component and/or an oscillating component. 
     When receiving the power signal  116  and when exposed to a condition  114 , an electrical characteristic of the sensor affects  118  the power signal. When the power signal change detection circuit  112  is enabled, it detects the affect  118  on the power signal as a result of the electrical characteristic of the sensor. For example, the power signal is a 1.5 voltage signal and, under a first condition, the sensor draws 1 milliamp of current, which corresponds to an impedance of 1.5 K Ohms. Under a second conditions, the power signal remains at 1.5 volts and the current increases to 1.5 milliamps. As such, from condition 1 to condition 2, the impedance of the sensor changed from 1.5 K Ohms to 1 K Ohms. The power signal change detection circuit  112  determines this change and generates a representative signal  120  of the change to the power signal. 
     As another example, the power signal is a 1.5 voltage signal and, under a first condition, the sensor draws 1 milliamp of current, which corresponds to an impedance of 1.5 K Ohms. Under a second conditions, the power signal drops to 1.3 volts and the current increases to 1.3 milliamps. As such, from condition 1 to condition 2, the impedance of the sensor changed from 1.5 K Ohms to 1 K Ohms. The power signal change detection circuit  112  determines this change and generates a representative signal  120  of the change to the power signal. 
     The power signal  116  includes a DC component  122  and/or an oscillating component  124  as shown in  FIG.  7   . The oscillating component  124  includes a sinusoidal signal, a square wave signal, a triangular wave signal, a multiple level signal (e.g., has varying magnitude over time with respect to the DC component), and/or a polygonal signal (e.g., has a symmetrical or asymmetrical polygonal shape with respect to the DC component). Note that the power signal is shown without affect from the sensor as the result of a condition or changing condition. 
     In an embodiment, power generating circuit  110  varies frequency of the oscillating component  124  of the power signal  116  so that it can be tuned to the impedance of the sensor and/or to be off-set in frequency from other power signals in a system. For example, a capacitance sensor&#39;s impedance decreases with frequency. As such, if the frequency of the oscillating component is too high with respect to the capacitance, the capacitor looks like a short and variances in capacitances will be missed. Similarly, if the frequency of the oscillating component is too low with respect to the capacitance, the capacitor looks like an open and variances in capacitances will be missed. 
     In an embodiment, the power generating circuit  110  varies magnitude of the DC component  122  and/or the oscillating component  124  to improve resolution of sensing and/or to adjust power consumption of sensing. In addition, the power generating circuit  110  generates the drive signal  110  such that the magnitude of the oscillating component  124  is less than magnitude of the DC component  122 . 
       FIG.  6 A  is a schematic block diagram of a drive center circuit  28 - a   1  coupled to a sensor  30 . The drive sense-sense circuit  28 - a   1  includes a signal source circuit  111 , a signal change detection circuit  113 , and a power source  115 . The power source  115  (e.g., a battery, a power supply, a current source, etc.) generates a voltage and/or current that is combined with a signal  117 , which is produced by the signal source circuit  111 . The combined signal is supplied to the sensor  30 . 
     The signal source circuit  111  may be a voltage supply circuit (e.g., a battery, a linear regulator, an unregulated DC-to-DC converter, etc.) to produce a voltage-based signal  117 , a current supply circuit (e.g., a current source circuit, a current mirror circuit, etc.) to produce a current-based signal  117 , or a circuit that provide a desired power level to the sensor and substantially matches impedance of the sensor. The signal source circuit  111  generates the signal  117  to include a DC (direct current) component and/or an oscillating component. 
     When receiving the combined signal (e.g., signal  117  and power from the power source) and when exposed to a condition  114 , an electrical characteristic of the sensor affects  119  the signal. When the signal change detection circuit  113  is enabled, it detects the affect  119  on the signal as a result of the electrical characteristic of the sensor. 
       FIG.  8    is an example of a sensor graph that plots an electrical characteristic versus a condition. The sensor has a substantially linear region in which an incremental change in a condition produces a corresponding incremental change in the electrical characteristic. The graph shows two types of electrical characteristics: one that increases as the condition increases and the other that decreases and the condition increases. As an example of the first type, impedance of a temperature sensor increases and the temperature increases. As an example of a second type, a capacitance touch sensor decreases in capacitance as a touch is sensed. 
       FIG.  9    is a schematic block diagram of another example of a power signal graph in which the electrical characteristic or change in electrical characteristic of the sensor is affecting the power signal. In this example, the effect of the electrical characteristic or change in electrical characteristic of the sensor reduced the DC component but had little to no effect on the oscillating component. For example, the electrical characteristic is resistance. In this example, the resistance or change in resistance of the sensor decreased the power signal, inferring an increase in resistance for a relatively constant current. 
       FIG.  10    is a schematic block diagram of another example of a power signal graph in which the electrical characteristic or change in electrical characteristic of the sensor is affecting the power signal. In this example, the effect of the electrical characteristic or change in electrical characteristic of the sensor reduced magnitude of the oscillating component but had little to no effect on the DC component. For example, the electrical characteristic is impedance of a capacitor and/or an inductor. In this example, the impedance or change in impedance of the sensor decreased the magnitude of the oscillating signal component, inferring an increase in impedance for a relatively constant current. 
       FIG.  11    is a schematic block diagram of another example of a power signal graph in which the electrical characteristic or change in electrical characteristic of the sensor is affecting the power signal. In this example, the effect of the electrical characteristic or change in electrical characteristic of the sensor shifted frequency of the oscillating component but had little to no effect on the DC component. For example, the electrical characteristic is reactance of a capacitor and/or an inductor. In this example, the reactance or change in reactance of the sensor shifted frequency of the oscillating signal component, inferring an increase in reactance (e.g., sensor is functioning as an integrator or phase shift circuit). 
       FIG.  11 A  is a schematic block diagram of another example of a power signal graph in which the electrical characteristic or change in electrical characteristic of the sensor is affecting the power signal. In this example, the effect of the electrical characteristic or change in electrical characteristic of the sensor changes the frequency of the oscillating component but had little to no effect on the DC component. For example, the sensor includes two transducers that oscillate at different frequencies. The first transducer receives the power signal at a frequency of f 1  and converts it into a first physical condition. The second transducer is stimulated by the first physical condition to create an electrical signal at a different frequency f 2 . In this example, the first and second transducers of the sensor change the frequency of the oscillating signal component, which allows for more granular sensing and/or a broader range of sensing. 
       FIG.  12    is a schematic block diagram of an embodiment of a power signal change detection circuit  112  receiving the affected power signal  118  and the power signal  116  as generated to produce, therefrom, the signal representative  120  of the power signal change. The affect  118  on the power signal is the result of an electrical characteristic and/or change in the electrical characteristic of a sensor; a few examples of the affects are shown in  FIGS.  8 - 11 A . 
     In an embodiment, the power signal change detection circuit  112  detect a change in the DC component  122  and/or the oscillating component  124  of the power signal  116 . The power signal change detection circuit  112  then generates the signal representative  120  of the change to the power signal based on the change to the power signal. For example, the change to the power signal results from the impedance of the sensor and/or a change in impedance of the sensor. The representative signal  120  is reflective of the change in the power signal and/or in the change in the sensor&#39;s impedance. 
     In an embodiment, the power signal change detection circuit  112  is operable to detect a change to the oscillating component at a frequency, which may be a phase shift, frequency change, and/or change in magnitude of the oscillating component. The power signal change detection circuit  112  is also operable to generate the signal representative of the change to the power signal based on the change to the oscillating component at the frequency. The power signal change detection circuit  112  is further operable to provide feedback to the power source circuit  110  regarding the oscillating component. The feedback allows the power source circuit  110  to regulate the oscillating component at the desired frequency, phase, and/or magnitude. 
       FIG.  13    is a schematic block diagram of another embodiment of a drive sense circuit  28 - a   2  that includes a current source  110 - 1  and a power signal change detection circuit  112 - a   1 . The power signal change detection circuit  112 - a   1  includes a power source reference circuit  130  and a comparator  132 . The current source  110 - 1  may be an independent current source, a dependent current source, a current mirror circuit, etc. 
     In an example of operation, the power source reference circuit  130  provides a current reference  134  with DC and oscillating components to the current source  110 - 1 . The current source generates a current as the power signal  116  based on the current reference  134 . An electrical characteristic of the sensor  30  has an effect on the current power signal  116 . For example, if the impedance of the sensor decreases and the current power signal  116  remains substantially unchanged, the voltage across the sensor is decreased. 
     The comparator  132  compares the current reference  134  with the affected power signal  118  to produce the signal  120  that is representative of the change to the power signal. For example, the current reference signal  134  corresponds to a given current (I) times a given impedance (Z). The current reference generates the power signal to produce the given current (I). If the impedance of the sensor  30  substantially matches the given impedance (Z), then the comparator&#39;s output is reflective of the impedances substantially matching. If the impedance of the sensor  30  is greater than the given impedance (Z), then the comparator&#39;s output is indicative of how much greater the impedance of the sensor  30  is than that of the given impedance (Z). If the impedance of the sensor  30  is less than the given impedance (Z), then the comparator&#39;s output is indicative of how much less the impedance of the sensor  30  is than that of the given impedance (Z). 
       FIG.  14    is a schematic block diagram of another embodiment of a drive sense circuit  28 - a   3  that includes a voltage source  110 - 2  and a power signal change detection circuit  112 - a   2 . The power signal change detection circuit  112 - a   2  includes a power source reference circuit  130 - 2  and a comparator  132 - 2 . The voltage source  110 - 2  may be a battery, a linear regulator, a DC-DC converter, etc. 
     In an example of operation, the power source reference circuit  130 - 2  provides a voltage reference  136  with DC and oscillating components to the voltage source  110 - 2 . The voltage source generates a voltage as the power signal  116  based on the voltage reference  136 . An electrical characteristic of the sensor  30  has an effect on the voltage power signal  116 . For example, if the impedance of the sensor decreases and the voltage power signal  116  remains substantially unchanged, the current through the sensor is increased. 
     The comparator  132  compares the voltage reference  136  with the affected power signal  118  to produce the signal  120  that is representative of the change to the power signal. For example, the voltage reference signal  134  corresponds to a given voltage (V) divided by a given impedance (Z). The voltage reference generates the power signal to produce the given voltage (V). If the impedance of the sensor  30  substantially matches the given impedance (Z), then the comparator&#39;s output is reflective of the impedances substantially matching. If the impedance of the sensor  30  is greater than the given impedance (Z), then the comparator&#39;s output is indicative of how much greater the impedance of the sensor  30  is than that of the given impedance (Z). If the impedance of the sensor  30  is less than the given impedance (Z), then the comparator&#39;s output is indicative of how much less the impedance of the sensor  30  is than that of the given impedance (Z). 
       FIG.  15    is a schematic block diagram of another embodiment of a drive sense circuit  28 - a   4  that includes the power source circuit  110 , the power signal change detection circuit  112 , an analog to digital converter  140 , and a driver  142 . The power source circuit  110  and the power signal change detection circuit  112  function as previously discussed with reference to  FIG.  13    to produce a signal  120  that is representative of a power signal change. 
     In this embodiment, the power source circuit  110  provides its output to the driver  142 , which functions to increase the power (e.g., increase voltage and/or current) of the power signal produced by the power source circuit  110 . The driver  142  provides the power signal  116  to the sensor  30 . With a driver, which may be a power amplifier, a low impedance sensor  30  may be used of specific types for sensing applications. 
     The analog to digital converter  140  converts the signal  120  that represents the power signal change into a digital signal  144 . The digital signal  144  is provided to the processing module  42  via a connection between the drive-sense circuit and the processing module. The processing module converts the digital signal into a relative value of the condition to which the sensor is exposed. The connection between the drive-sense circuit  28 - a   4  and the processing module  42  depends on whether the drive-sense circuit is internal or external to the computing device of the processing module. If internal, then the drive-sense circuit is connected to the processing module via a PCI bus or the like. If the drive-sense circuit is external to the processing module, then the connection is a USB connection, a Bluetooth connection, a WLAN connection, an internet connection, and/or a WAN connection. 
       FIG.  16    is a schematic block diagram of another embodiment of a drive sense circuit  28 - b  includes a change detection circuit  150 , a regulation circuit  152 , and a power source circuit  154 . The drive-sense circuit  28 - b  is coupled to the sensor  30 , which includes a transducer that has varying electrical characteristics (e.g., capacitance, inductance, impedance, current, voltage, etc.) based on varying physical conditions  114  (e.g., pressure, temperature, biological, chemical, etc.). 
     The power source circuit  154  is operably coupled to the sensor  30  and, when enabled (e.g., from a control signal from the processing module  42 , power is applied, a switch is closed, a reference signal is received, etc.) provides a power signal  158  to the sensor  30 . The power source circuit  154  may be a voltage supply circuit (e.g., a battery, a linear regulator, an unregulated DC-to-DC converter, etc.) to produce a voltage-based power signal or a current supply circuit (e.g., a current source circuit, a current mirror circuit, etc.) to produce a current-based power signal. The power source circuit  154  generates the power signal  158  to include a DC (direct current) component and an oscillating component. 
     When receiving the power signal  158  and when exposed to a condition  114 , an electrical characteristic of the sensor affects  160  the power signal. When the change detection circuit  150  is enabled, it detects the affect  160  on the power signal as a result of the electrical characteristic of the sensor  30 . The change detection circuit  150  is further operable to generate a signal  120  that is representative of change to the power signal based on the detected effect on the power signal. 
     The regulation circuit  152 , when its enabled, generates regulation signal  156  to regulate the DC component to a desired DC level and/or regulate the oscillating component to a desired oscillating level (e.g., magnitude, phase, and/or frequency) based on the signal  120  that is representative of the change to the power signal. The power source circuit  154  utilizes the regulation signal  156  to keep the power signal at a desired setting  158  regardless of the electrical characteristic of the sensor. In this manner, the amount of regulation is indicative of the affect the electrical characteristic had on the power signal. 
     In an example, the power source circuit  158  is a DC-DC converter operable to provide a regulated power signal having DC and AC components. The change detection circuit  150  is a comparator and the regulation circuit  152  is a pulse width modulator to produce the regulation signal  156 . The comparator compares the power signal  158 , which is affected by the sensor, with a reference signal that includes DC and AC components. When the electrical characteristics is at a first level (e.g., a first impedance), the power signal is regulated to provide a voltage and current such that the power signal substantially resembles the reference signal. 
     When the electrical characteristics changes to a second level (e.g., a second impedance), the change detection circuit  150  detects a change in the DC and/or AC component of the power signal  158  and generates the representative signal  120 , which indicates the changes. The regulation circuit  152  detects the change in the representative signal  120  and creates the regulation signal to substantially remove the effect on the power signal. The regulation of the power signal  158  may be done by regulating the magnitude of the DC and/or AC components, by adjusting the frequency of AC component, and/or by adjusting the phase of the AC component. 
       FIG.  17    is a schematic block diagram of another embodiment of a drive sense circuit  28 - b   1  that includes a current source  154 - 1  and a change detection circuit  150 - 1 . The change detection circuit  150 - 1  includes a power source reference circuit  162  and a comparator  164 . The current source  154 - 1  may be an independent current source, a dependent current source, a current mirror circuit, etc. 
     In an example of operation, the power source reference circuit  162  provides a current reference with DC and/or oscillating components to the comparator  164 . The comparator  164  compares the reference current with the current power signal  158  generated by the current source  154 - 1  and produces, based on the comparison, the representative signal  120 . 
     The regulation circuit  152 , which includes a feedback circuit  166  (e.g., a dependent current source biasing circuit, a wire, etc.), generates a regulation signal  156 - 1  based on the representative signal  120  and provides the regulation signal to the current source  154 - 1 . The current source generates a regulated current as the power signal  116  based on the regulation signal  156 - 1 . 
     As an example, the current reference signal corresponds to a given current (I) times a given impedance (Z). The current source  154 - 1  generates the power signal to produce the given current (I). If the impedance of the sensor  30  substantially matches the given impedance (Z), then the comparator&#39;s output is reflective of the impedances substantially matching. If the impedance of the sensor  30  is greater than the given impedance (Z), then the comparator&#39;s output is indicative of how much greater the impedance of the sensor  30  is than that of the given impedance (Z). If the impedance of the sensor  30  is less than the given impedance (Z), then the comparator&#39;s output is indicative of how much less the impedance of the sensor  30  is than that of the given impedance (Z). The regulation circuit functions to account for the variations in the impedance of the sensor and to ensure that the current source produces a regulated current source (e.g., it remains substantially at the given current (I)). 
       FIG.  18    is a schematic block diagram of another embodiment of a drive sense circuit  28 - b   2  that includes a voltage source  154 - 2  and a change detection circuit  150 - 2 . The change detection circuit  150 - 2  includes a power source reference circuit  162 - 2  and a comparator  164 - 2 . The voltage source  154 - 2  may be a linear regulator, a DC-DC converter, etc. 
     In an example of operation, the power source reference circuit  162 - 2  provides a voltage reference with DC and oscillating components to the comparator  164 - 2 . The comparator  164 - 2  compares the reference voltage with the voltage power signal  158  generated by the voltage source  154 - 2  and produces, based on the comparison, the representative signal  120 . 
     The regulation circuit  152 , which includes a feedback circuit  166 - 2  (e.g., a power supply regulation circuit, a bias circuit, a wire, etc.), generates a regulation signal  156 - 2  based on the representative signal  120  and provides the regulation signal to the voltage source  154 - 2 . The voltage source generates a regulated voltage as the power signal  116  based on the regulation signal  156 - 1 . 
     As an example, the voltage reference signal corresponds to a given voltage (V) divided by a given impedance (Z). The voltage source  154 - 2  generates the power signal to produce the given voltage (V). If the impedance of the sensor  30  substantially matches the given impedance (Z), then the comparator&#39;s output is reflective of the impedances substantially matching. If the impedance of the sensor  30  is greater than the given impedance (Z), then the comparator&#39;s output is indicative of how much greater the impedance of the sensor  30  is than that of the given impedance (Z). If the impedance of the sensor  30  is less than the given impedance (Z), then the comparator&#39;s output is indicative of how much less the impedance of the sensor  30  is than that of the given impedance (Z). The regulation circuit functions to account for the variations in the impedance of the sensor and to ensure that the voltage source produces a regulated voltage source (e.g., it remains substantially at the given voltage (V)). 
       FIG.  19    is a schematic block diagram of another embodiment of a drive sense circuit  28 - b   3  that includes the power source circuit  154 , the change detection circuit  150 , the regulation circuit  152 , an analog to digital converter  140 , and a driver  142 . The power source circuit  154 , the regulation circuit  152 , and the change detection circuit  150  function as previously discussed with reference to  FIG.  16    to produce the regulation signal  156  and the signal  120  that is representative of a power signal change. 
     In this embodiment, the power source circuit  154  provides its output to the driver  142 , which functions to increase the power (e.g., increase voltage and/or current) of the power signal. The driver  142  provides the power signal  116  to the sensor  30 . With a driver, which may be a power amplifier, a low impedance sensor  30  may be used for specific types of sensing applications. 
     The analog to digital converter  140  converts the signal  120  that represents the power signal change into a digital signal  144 . The digital signal  144  is provided to the processing module  42  via a connection between the drive-sense circuit and the processing module. 
       FIG.  20    is a schematic block diagram of another embodiment of a drive-sense circuit  28  that includes a power supply circuit  155  and an operational amplifier (op amp) or comparator  172 . The power supply circuit  155  may be implemented in a variety of ways. For example, the power supply circuit  155  is a linear regulator that steps down a DC input voltage (DC in) to produce the power signal  174  based on a regulation signal  156 - 3 . As another example, the power supply circuit  155  is a DC-DC converter that steps up or steps down the DC input voltage based on the regulation signal to produce the power signal  174 . 
     The op amp  172  compares the power signal  174  with the power signal reference to produce the regulation signal  156 - 3 , which is also the signal  120  representing a power signal change. In a specific embodiment, the power supply circuit  155  includes a P-channel FET (field effect transistor) and a bias circuit. The source of the P-channel FET is coupled to the DC input, the gate to the bias circuit, and the drain is coupled to provide the power signal  174 . The bias circuit receives the regulation signal  156 - 3  and adjusts a gate-source voltage such that the voltage of the power signal  174  substantially matches the voltage of the power signal reference  170 . For example, if the power signal reference has a DC component and/or an oscillating component as shown in  FIG.  7   , then the power signal  174  will have a substantially similar DC component and/or oscillating component. 
     When the power signal  174  is provided to a sensor and the sensor is exposed to a condition, an electrical characteristic of the sensor will affect the power signal. The control loop that regulates the voltage of the power signal  174  to substantially match the voltage of the power reference signal  170  will adjust the regulation signal to compensate for the affects the sensor has on the power signal  174 . The compensation corresponds to the affect the electrical characteristic of the sensor has on the power signal and is representative of the condition being sensed by the sensor. Thus, the regulation signal  156 - 3  provides both the regulation of the power supply circuit  155  and the signal  120  that represents the effect on the power signal. 
       FIG.  21    is a schematic block diagram of another embodiment of a drive-sense circuit  28  that includes a dependent current source  182  and a transimpedance amplifier  180 , which functions as a current comparator in this embodiment. The dependent current source  182  may be implemented in a variety of ways. For example, the dependent current source  182  is a current mirror circuit sourced via a DC input voltage (DC in) to produce the power signal  184  based on a regulation signal  156 - 3 . As another example, the dependent current source  182  is voltage controlled current source. As yet another example, the dependent current source  182  is current controlled current source. 
     The transimpedance amplifier  180  compares current of the power signal  174  with current of the power signal reference  186  to produce the regulation signal  156 - 4 , which is also the signal  120  representing a power signal change. In a specific embodiment, the power supply circuit  155  includes a P-channel FET (field effect transistor) and a bias circuit. The source of the P-channel FET is coupled to the DC input, the gate to the bias circuit, and the drain is coupled to provide the power signal  184 . The bias circuit receives the regulation signal  156 - 4  and adjusts a gate-source voltage such that the current of the power signal  184  substantially matches the current of the power signal reference  186 . 
     When the current of the power signal  184  is provided to a sensor and the sensor is exposed to a condition, an electrical characteristic of the sensor will affect the power signal. The control loop that regulates the current of the power signal  184  to substantially match the current of the power reference signal  186  will adjust the regulation signal to compensate for the affects the sensor has on the power signal  184 . The compensation corresponds to the affect the electrical characteristic of the sensor has on the power signal and is representative of the condition being sensed by the sensor. Thus, the regulation signal  156 - 4  provides both the regulation of the dependent current source  182  and the signal  120  that represents the effect on the power signal. 
       FIG.  22    is a schematic block diagram of another embodiment of a drive sense circuit  28 - c , which is coupled to a sensor  30 . The drive sense circuit  28 - c  includes analog circuitry  190  and digital circuitry  192 . When the analog circuitry  190  is enabled, it is operable to generate a regulated source signal  196  based on an analog regulation signal  204 . The analog circuitry is enabled in a variety of ways. For example, the analog circuitry  190  is enable when power is applied to the drive sense circuit  28 - c . As another example, the analog circuitry  190  is enabled when the drive sense circuit receives a control signal from the processing module. 
     The analog circuitry  190  provides the regulated source signal  196  to the sensor  30 . The regulated source signal  196  may be a regulated current signal, a regulated voltage signal, or a regulated impedance signal. When the sensor  30  is exposed to a condition  114 , an electrical characteristic of the sensor affects  198  the regulated source signal. 
     In addition to generating the regulated source signal  196 , the analog circuitry  190  also generates a reference source signal  194  at a desired source level. For example, the reference source signal  194  is generated to include a DC component having a magnitude and/or an oscillating component having a waveform (e.g., sinusoidal, square, triangular, polygonal, multiple step, etc.), a frequency, a phase, and a magnitude. The analog circuitry  190  is further operable to compare the regulated source signal  196  to the reference source signal  194  to produce a comparison signal  200 . The comparison signal  200  corresponds to the affect the electrical characteristic of the sensor has on the regulated source signal and is representative of the condition  114  being sensed by the sensor  30 . 
     When the digital circuitry is enabled, it is operable to convert the comparison signal  200  into a digital signal  202 . The digital signal is a digital representation of the comparison signal and, as such, corresponds to the affect the electrical characteristic of the sensor has on the regulated source signal and is representative of the condition  114  being sensed by the sensor  30 . The digital circuitry  192  is further operable to convert the digital signal  202  into the analog regulation signal  204 . 
       FIG.  23    is a schematic block diagram of another embodiment of a drive sense circuit  28 - c   1  that includes the analog circuitry  190  and the digital circuitry  192 . The analog circuitry  190  includes a dependent current source  216 , a comparator  210 , an analog portion of an analog to digital converter  212 , and an analog portion of a digital to analog converter  214 . The digital circuitry  192  includes a digital portion of the analog to digital converter  212 , and a digital portion of the digital to analog converter  214 . The analog to digital converter (ADC)  212  may be a flash ADC, a successive approximation ADC, a ramp-compare ADC, a Wilkinson ADC, an integrating ADC, a delta encoded ADC, and/or a sigma-delta ADC. The digital to analog converter (DAC)  214  may be a sigma-delta DAC, a pulse width modulator DAC, a binary weighted DAC, a successive approximation DAC, and/or a thermometer-coded DAC. 
     The dependent current source  216  generates the regulated source signal  196 - 1  as a regulated current signal based on the analog regulation signal  220 . The comparator  210  compares the regulated source signal  196 - 1  with a reference source signal  194 - 1 , which is a current reference signal having a DC component and/or an oscillating component. The comparison signal  218  corresponds to the effect on the regulated source signal  196 - 1  and is representative of the condition  114  being sensed by the sensor  30 . The comparator  210  provides the comparison signal  218  to the analog to digital converter  212 , which generates the digital signal  202 . The digital to analog converter  214  converts the digital signal into the analog regulation signals  220 . 
       FIG.  24    is a schematic block diagram of another embodiment of a drive sense circuit  28 - c   2  that includes the analog circuitry  190  and the digital circuitry  192 . The analog circuitry  190  includes a voltage source circuit  216 , a change detection circuit  224 , an analog portion of an analog to digital converter  212 - 2 , and an analog portion of a digital to analog converter  214 - 2 . The digital circuitry  192  includes a digital portion of the analog to digital converter  212 - 2 , and a digital portion of the digital to analog converter  214 - 2 . The analog to digital converter  212 - 2  and the digital to analog converter  214 - 2  are one or more of the types discussed with reference to  FIG.  23   . 
     The voltage source circuit  226  (e.g., a power supply, a linear regulator, a biased transistor, etc.) generates the regulated source signal  196 - 2  as a regulated voltage signal based on the analog regulation signal  220 - 2 . The change detection circuit  224  (e.g., an op amp, a comparator, etc.) compares the regulated source signal  196 - 2  with a reference source signal  194 - 2 , which is a voltage reference signal having a DC component and/or an oscillating component. The comparison signal  218 - 2  corresponds to the effect on the regulated source signal  196 - 2  and is representative of the condition  114  being sensed by the sensor  30 . The change detection circuit  224  provides the comparison signal  218 - 2  to the analog to digital converter  212 - 2 , which generates the digital signal  202 . The digital to analog converter  214 - 2  converts the digital signal into the analog regulation signals  220 - 2 . 
       FIG.  24 A  is a schematic block diagram of another embodiment of a drive sense circuit  28 - c   3  coupled to a load  201 . The drive sense circuit  28 - c   3  includes an analog front end (AFE)  203  and a digital back end (DBE)  205 . The analog front end may be implemented in accordance with an embodiment of one or more of  FIGS.  1 - 23  and  25 - 38   . The digital back end may be implemented in accordance with an embodiment as disclosed in application Ser. No. 16/266,953, titled “RECEIVE ANALOG TO DIGITAL CIRCUIT OF A LOW VOLTAGE DRIVE CIRCUIT DATA COMMUNICATION SYSTEM”, filed on Feb. 4, 2019, and/or an embodiment as disclosed in application Ser. No. 17/168,962, titled “PARALLEL PROCESSING OF MULTIPLE CHANNELS WITH VERY NARROW BANDPASS DIGITAL FILTERING”, filed on Feb. 5, 2021. In general, the drive sense circuit  28 - c   3  generates a digital sensed value  207  that represents a characteristic  209  (e.g., impedance, current, etc.) of the load  201 . 
     In an example of operation, when the drive sense circuit  28 - c   3  is enabled, the analog front end  203  generates an analog drive sense signal  211  based on analog reference signal  199 . The analog reference signal  211  includes a varying component (e.g., an alternating current signal that is one of a sinusoid, square wave, triangle wave, sawtooth wave, etc.) and/or a constant component (e.g., a constant current). 
     The varying component has a magnitude that is substantially less (e.g., 50% less, an order of magnitude less, 95% less, 99% less, etc.) than a supply rail power of the drive sense circuit  28 - c   3 . As a specific example, the magnitude of the varying component is 10 mV (millivolts) and the supply rail voltage is greater than or equal to 1 V. As another specific example, the magnitude of the varying component is 200 mV and the supply rail voltage is 1 V. As yet another specific example, the magnitude of the varying component is 1 microamp and the supply rail current is 100 microamps. As yet another specific example, the magnitude of the varying component is 40 microamps and the supply rail current is greater than or equal to 100 microamps. 
     When the drive sense circuit  28 - c   3  is enabled and coupled to the load  201 , the drive sense circuit  28 - c   3  drives the load  201  with the analog drive-sense signal  211 . The load  201  has a characteristic  209  that includes one or more of a voltage, a current and an impedance. For example, during a first time period, the load has a current of 50 microamps, a voltage of 1 volt and an impedance of 20 kilohms. 
     The analog front end (AFE)  203  detects an analog signal variation in the analog drive sense signal  211  based on the characteristic of the load. For example, when the load current changes (e.g., to 45 microamps), the changed current causes a variation  213  of the analog drive sense signal. The AFE  203  produces an analog signal variation signal  217  based on the variation  213  on signal  211  and the analog reference signal  199 . The AFE  203  also produces an AFE feedback signal  215  based on the analog signal variation  217 . The AFE utilizes the AFE feedback  215  to keep the analog drive sense signal  211  substantially equal to the analog reference signal  199 . 
     The digital back-end (DBE)  205  converts the analog signal variation  217  into a digital sensed value  207  that represents the characteristic. As a specific example, the digital back-end converts the analog signal variation into a digital sensed value of 5, where “5” represents the sensed load current of 45 microamps. 
       FIG.  24 B  is a schematic block diagram of another embodiment of a drive sense circuit  28 - c   4  coupled to a load  201 . The drive sense circuit  28 - c   4  includes an analog front end  203  and a digital back end  205 . In general, the drive sense circuit  28 - c   4  generates a digital sensed value  207  that represents a characteristic  209  of the load  201 . 
     In an example of operation, when the drive sense circuit  28 - c   4  is enabled, the analog front end  203  generates an analog drive sense signal  211  based on analog reference signal  199 . The analog reference signal  211  includes a varying component (e.g., an alternating current signal that is one of a sinusoid, square wave, triangle wave, sawtooth wave, etc.) and/or a constant component (e.g., a constant current). 
     The varying component has a magnitude that is substantially less (e.g., 50% less, an order of magnitude less, 95% less, etc.) than a supply rail power of the drive sense circuit  28 - c   4 . As a specific example, the magnitude of the varying component is 25 mV (millivolts) and the supply rail voltage is greater than or equal to 1V. As another specific example, the magnitude of the varying component is 150 mV and the supply rail voltage is 1V. As yet another specific example, the magnitude of the varying component is 2 microamps and the supply current is 50 microamps. As yet another specific example, the magnitude of the varying component is 40 microamps and the supply current is greater than or equal to 100 microamps. 
     When the drive sense circuit  28 - c   4  is enabled and coupled to the load  201 , the drive sense circuit  28 - c   4  drives the load  201  with the analog drive-sense signal  211 . The load  201  has a characteristic  209  that includes one or more of a voltage, a current and an impedance. For example, during a first time period, the load has a voltage of 500 mV. The analog front end  203  detects an analog signal variation in the analog drive sense signal  211  based on the characteristic of the load. For example, when the load current changes (e.g., to 525 mV), the changed voltage causes a variation  213  of the analog drive sense signal. The AFE  203  produces an analog signal variation signal  217  based on the variation  213  on signal  211  and the analog reference signal  199 . 
     The digital back-end  205  converts the analog signal variation  217  into a digital sensed value  207  that represents the characteristic. As a specific example, the digital back-end converts the analog signal variation  217  into a digital sensed value of 43, where “43” represents a load voltage of 525 mV. As another specific example, the digital back-end converts the analog signal variation  217  into a digital sensed value of 525, where “525” represents the load voltage of 525 mV. 
     The digital backend  205  may also generate a DBE feedback signal  219  from the analog signal variation  217  and provide the DBE feedback signal  219  to the analog front end  203 . In an embodiment, the DBE feedback is a digital signal, and the AFE  203  converts the DBE feedback  219  into an analog feedback signal. Alternatively, the DBE  205  converts the DBE feedback  219  to an analog feedback signal before providing it to the AFE  203 . The AFE utilizes the DBE feedback  215  to keep the analog drive sense signal  211  substantially equal to the analog reference signal  199 . 
       FIG.  25    is a schematic block diagram of another embodiment of a drive sense circuit  28 -d coupled to a variable impedance sensor  30 - 1 . The drive sense circuit  28 - d  includes a voltage (V) reference circuit  230 , a current (I) loop correction circuit  232 , and a regulated current (I) source circuit  234 . In general, the drive sense circuit  28 - d  regulates the current applied to the sensor and keeps the voltage constant to sense an impedance (Z) of the sensor  30 - 1  in relation to a sensor voltage  246  and a voltage reference  236 . 
     When the drive sense circuit  28 - d  is enabled, the regulated current source circuit  234  is operable to generate a regulated current signal  238  based on an analog regulation signal  242 . The regulated current source circuit  234  generates the regulated current signal  238  such that the sensor voltage  246  substantially matches a voltage reference  236  produced by the V reference circuit  230 . 
     The V reference circuit  230  (which may be a bandgap reference, a regulator, a divider network, an AC generator, and/or combining circuit) generates the voltage reference  236  to include a DC component and/or at least one oscillating component. For example, the V reference circuit generates a DC component to have a magnitude between 1 and 3 volts, generates a first sinusoidal oscillating component at frequency 1, and generates a second sinusoidal oscillating component at frequency 2. As a specific example, the first sinusoidal oscillating component at frequency 1 is used to sense self-touch on a touch screen display and the second sinusoidal oscillating component at frequency 2 is used to sense mutual touch on the touch screen display. 
     The regulated current source circuit  234  provides the regulated current signal  238  to the sensor  30 - 1 . When the sensor  30 - 1  is exposed to a condition  114 - 1 , its impedance affects  240  the regulated current signal  238  based on V=I*Z. As such, the sensor voltage  246  is created as a result of the current (I) provided by the regulated current source circuit  234  and the impedance of the sensor  30 - 1 . As the impedance of the sensor  30 - 1  changes due to changing conditions  114 - 1 , the current provided by the regulated current source circuit  234  changes so that the sensor voltage  246  remains substantially equal to the voltage reference  236 , including the DC component and/or the oscillating component(s). 
     The current (I) loop correction circuit  232  is operable to generate a comparison signal  244  based on a comparison of the sensor voltage  246  with the voltage reference  236 . The effect of the impedance of the sensor on the regulated current signal  238  is detected by the I loop correction circuit  232  and captured by the comparison signal  244 . The I loop correction circuit  232  is further operable to convert the comparison signal  244  into a digital signal  202 , which is a digital representation of the affect the impedance of the sensor has on the regulated current signal and corresponds to the sensed condition  114 - 1 . The I loop correction circuit is further operable to convert the digital signal  202  into the analog regulation signal  242 , thereby creating a feedback loop to keep the sensor voltage  246  substantially equal to the voltage reference  236 . 
       FIG.  26    is a schematic block diagram of another embodiment of a drive sense circuit  28 - d   1  coupled to a variable impedance sensor  30 - 1 . The drive sense circuit  28 - d   1  includes the voltage (V) reference circuit  230 , a current (I) loop correction circuit  232 - 1 , and a regulated current (I) source circuit  234 - 1 . The regulated current (I) source circuit  234 - 1  includes a dependent current source and the I loop correction circuit  232 - 1  includes a voltage comparator or op amp  250 , an analog to digital converter  212 - 3  and a digital to analog converter  214 - 3 . The analog to digital converter  212 - 3  and the digital to analog converter  214 - 3  are one or more of the types discussed with reference to  FIG.  23   . 
     When the drive sense circuit  28 - d   1  is enabled, the regulated current source circuit  234 - 1  is operable to generate a regulated current signal  238 - 1  based on an analog regulation signal  242 - 1 . The regulated current source circuit  234 - 1  generates the regulated current signal  238 - 1  such that the sensor voltage  246 - 1  substantially matches the voltage reference  236  produced by the V reference circuit  230 . 
     The regulated current source circuit  234 - 1  provides the regulated current signal  238 - 1  to the sensor  30 - 1 . When the sensor  30 - 1  is exposed to a condition  114 - 1 , its impedance affects  240 - 1  the regulated current signal  238 - 1  based on V=I*Z. As such, the sensor voltage  246 - 1  is created as a result of the current (I) provided by the regulated current source circuit  234 - 1  and the impedance of the sensor  30 - 1 . As the impedance of the sensor  30 - 1  changes due to changing conditions  114 - 1 , the current provided by the regulated current source circuit  234 - 1  changes so that the sensor voltage  246 - 1  remains substantially equal to the voltage reference  236 - 1 , including the DC component and/or the oscillating component(s). 
     The comparator  250  compares the sensor voltage  246 - 1  with the voltage reference  236  to produce a comparison signal  244 - 1 . The effect of the impedance of the sensor on the regulated current signal  238 - 1  is captured by the comparison signal  244 - 1 . The analog to digital converter  212 - 3  converts the comparison signal  244 - 1  into a digital signal  202 , which is a digital representation of the affect the impedance of the sensor has on the regulated current signal and corresponds to the sensed condition  114 - 1 . The digital to analog converter  214 - 3  converts the digital signal  202  into the analog regulation signal  242 - 1 , thereby creating a feedback loop to keep the sensor voltage  246 - 1  substantially equal to the voltage reference  236 . 
       FIG.  26 A  is a schematic block diagram of another embodiment of a drive sense circuit coupled to a variable impedance sensor  30 - 1 . The drive sense circuit  28 - d   2  includes the voltage (V) reference circuit  230 , a current (I) loop correction circuit  232 - 2 , and a regulated current (I) source circuit  234 - 2 . The regulated current (I) source circuit  234 - 2  includes a dependent current source and the I loop correction circuit  232 - 2  includes a voltage comparator or op amp  250 , and an analog to digital converter  212 - 3   a.  The analog to digital converter  212 - 3   a  is one or more of the types discussed with reference to  FIG.  23   . 
     When the drive sense circuit  28 - d   2  is enabled, the regulated current source circuit  234 - 2  is operable to generate a regulated current signal  238 - 2  based on a comparison signal  244 - 2 . The regulated current source circuit  234 - 2  generates the regulated current signal  238 - 2  such that the sensor voltage  246 - 2  substantially matches the voltage reference  236  produced by the V reference circuit  230 . In an example, the comparison signal operates similar to the analog regulation signal  242 - 1  of  FIG.  26    to create a feedback loop to keep the sensor voltage  246 - 1  substantially equal to the voltage reference  236 . 
     The regulated current source circuit  234 - 2  provides the regulated current signal  238 - 2  to the sensor  30 - 1 . When the sensor  30 - 1  is exposed to a condition  114 - 2 , its impedance affects  240 - 2  the regulated current signal  238 - 2  based on V=I*Z. As such, the sensor voltage  246 - 2  is created as a result of the current (I) provided by the regulated current source circuit  234 - 2  and the impedance of the variable impedance sensor  30 - 2 . As the impedance of the variable impedance sensor  30 - 2  changes due to changing conditions  114 - 2 , the current provided by the regulated current source circuit  234 - 2  changes so that the sensor voltage  246 - 2  remains substantially equal to the voltage reference  236 , including the DC component and/or the oscillating component(s). 
     The comparator  250  compares the sensor voltage  246 - 2  with the voltage reference  236  to produce a comparison signal  244 - 2 . The effect of the impedance of the sensor on the regulated current signal  238 - 2  is captured by the comparison signal  244 - 2 . The analog to digital converter  212 - 3   a  converts the comparison signal  244 - 2  into a digital signal  202 , which is a digital representation of the affect the impedance of the sensor has on the regulated current signal and corresponds to the sensed condition  114 - 2 . 
       FIG.  27    is a schematic block diagram of another embodiment of a drive sense circuit  28 - e  coupled to a variable impedance sensor  30 - 1 . The drive sense circuit  28 - e  includes a current (I) reference circuit  260 , a voltage (V) loop correction circuit  262 , and a regulated voltage (V) source circuit  264 . In general, the drive sense circuit  28 - e  regulates the voltage applied to the sensor and keeps the current constant to sense an impedance (Z) of the sensor  30 - 1  in relation to a sensor current  272  and a current reference  270 . 
     When the drive sense circuit  28 - e  is enabled, the regulated voltage source circuit  264  is operable to generate a regulated voltage signal  266  based on an analog regulation signal  274 . The regulated voltage source circuit  264  generates the regulated voltage signal  266  such that the sensor current  272  substantially matches the current reference  270  produced by the I reference circuit  260 . 
     The I reference circuit  260  (which may be a biased dependent current source, an independent current source, a current mirror, an AC current generator, and/or combining circuit) generates the current reference  270  to include a DC component and/or at least one oscillating component. For example, the I reference circuit generates a DC component to have a magnitude between 100 micro-amps and 300 micro-amps (or other range), generates a first sinusoidal oscillating current component at frequency 1, and generates a second sinusoidal oscillating current component at frequency 2. As a specific example, the first sinusoidal oscillating current component at frequency 1 is used to sense self-touch on a touch screen display and the second sinusoidal oscillating current component at frequency 2 is used to sense mutual touch on the touch screen display. 
     The regulated voltage source circuit  264  provides the regulated voltage signal  266  to the sensor  30 - 1 . When the sensor  30 - 1  is exposed to a condition  114 - 1 , its impedance affects  240  the regulated voltage signal  266  based on Z=V/I. As such, the sensor current  272  is created as a result of the voltage (V) provided by the regulated voltage source circuit  264  and the impedance of the sensor  30 - 1 . As the impedance of the sensor  30 - 1  changes due to changing conditions  114 - 1 , the voltage provided by the regulated voltage source circuit  264  changes so that the sensor current  272  remains substantially equal to the current reference  270 , including the DC component and/or the oscillating component(s). 
     The voltage (V) loop correction circuit  262  is operable to generate a comparison signal  276  based on a comparison of the sensor current  272  with the current reference  270 . The effect of the impedance of the sensor on the regulated voltage signal  266  is detected by the V loop correction circuit  262  and is captured by the comparison signal  276 . The V loop correction circuit  262  is further operable to convert the comparison signal  276  into the digital signal  202 , which is a digital representation of the affect the impedance of the sensor has on the regulated voltage signal and corresponds to the sensed condition  114 - 1 . The V loop correction circuit is further operable to convert the digital signal  202  into the analog regulation signal  274 , thereby creating a feedback loop to keep the sensor current  272  substantially equal to the current reference  270 . 
       FIG.  28    is a schematic block diagram of another embodiment of a drive sense circuit  28 -el coupled to a variable impedance sensor  30 - 1 . The drive sense circuit  28 - e   1  includes a current (I) reference circuit  260 - 1 , a voltage (V) loop correction circuit  262 - 1 , and a regulated voltage (V) source circuit  264 - 1 . The I reference circuit  260 - 1  includes an independent current source to produce a reference current (I ref ). The V loop correction circuit  262 - 1  includes a current comparator (e.g., a transimpedance amplifier), an analog to digital converter  212 - 4  and a digital to analog converter  214 - 4 . The regulated voltage source  264 - 1  includes a P-channel FET and a current mirror  273 . The regulated voltage source  264 - 1  may further include a bias circuit (not shown) coupled between the gate and source of the P-channel FET. The analog to digital converter  212 - 4  and the digital to analog converter  214 - 4  are one or more of the types discussed with reference to  FIG.  23   . 
     When the drive sense circuit  28 - e   1  is enabled, the regulated voltage source circuit  264 - 1  is operable to generate a regulated voltage signal  266  based on an analog regulation signal  274 - 1 . The regulated voltage source circuit  264  generates the regulated voltage signal  266  such that the sensor current  272  substantially matches the current reference  270 , a multiple thereof, or a fraction thereof, produced by the I reference circuit  260 . The current mirror  273  mirrors the sensor current  272  and the mirrored current substantially matches the current reference  270 . The mirrored current produced by the current mirror  273  is equal to the sensor current  272 , is greater than the sensor current  272 , or is less than the sensor current  272  depending on the application and/or the sensor sensitivity. 
     The I reference circuit  260  (which may a DC current source and/or an AC current source) generates the current reference  270 - 1  to include a DC component and/or at least one oscillating component. For example, the I reference circuit generates a DC component to have a magnitude between 100 micro-amps and 300 micro-amps (or other range), generates a first sinusoidal oscillating current component at frequency 1, and generates a second sinusoidal oscillating current component at frequency 2. 
     The regulated voltage source circuit  264 - 1  provides the regulated voltage signal  266  to the sensor  30 - 1 . When the sensor  30 - 1  is exposed to a condition  114 - 1 , its impedance affects  240  the regulated voltage signal  266  based on Z=V/I. As such, the sensor current  272  is created as a result of the voltage (V) provided by the regulated voltage source circuit  264 - 1  and the impedance of the sensor  30 - 1 . As the impedance of the sensor  30 - 1  changes due to changing conditions  114 - 1 , the voltage provided by the regulated voltage source circuit  264 - 1  changes so that the mirrored current of the sensor current  272  remains substantially equal to the current reference  270 - 1 , including the DC component and/or the oscillating component(s). 
     The current comparator (comp) compares the mirrored current of the sensor current  272  with the current reference  270 - 1  to generate the comparison signal  276 . The effect of the impedance of the sensor on the regulated voltage signal  266  is captured by the comparison signal  276 . The analog to digital converter  212 - 4  converts the comparison signal  276  into the digital signal  202 , which is a digital representation of the affect the impedance of the sensor has on the regulated voltage signal and corresponds to the sensed condition  114 - 1 . The digital to analog converter  214 - 4  convert the digital signal  202  into the analog regulation signal  274 , thereby creating a feedback loop to keep the mirrored current of the sensor current  272  substantially equal to the current reference  270 - 1 . 
       FIG.  29    is a schematic block diagram of another embodiment of a drive sense circuit  28 - f  coupled to a variable current sensor  30 - 2 . The drive sense circuit  28 - f  includes an impedance (Z) reference circuit  280 , a voltage (V) loop correction circuit  282 , and a regulated voltage (V) source circuit  284 . In general, the drive sense circuit  28 - f  regulates the voltage applied to the sensor and keeps the sensor&#39;s impedance constant to sense a current (I) of the sensor  30 - 2  in relation to a sensor impedance  292  and an impedance (Z) reference  290 . Varying current of the sensor  30 - 2  is indicative of changes to the condition  114 - 2  being sensed (e.g., magnetic field, current flow, etc.), which may be used in motor monitoring applications, load sensing applications, electronic circuit applications, failure analysis applications, etc. 
     When the drive sense circuit  28 - f  is enabled, the regulated voltage source circuit  284  is operable to generate a regulated voltage signal  286  based on an analog regulation signal  294 . The regulated voltage source circuit  284  generates the regulated voltage signal  286  such that the sensor impedance  292  (e.g., capacitance, inductance, etc.) substantially matches the impedance reference  290  produced by the Z reference circuit  280 . 
     The Z reference circuit  280  (which may be a capacitor, an inductor, a circuit equivalent of a capacitor, a circuit equivalent of an inductor, a tunable capacitor bank, etc.) generates the impedance reference  290  to include a DC component and/or at least one oscillating (AC) component. For example, the Z reference circuit generates a DC component to have a desired resistance at DC and/or to have a first desired impedance at frequency 1, and have a second desired impedance at frequency 2. 
     The regulated voltage source circuit  284  provides the regulated voltage signal  286  to the sensor  30 - 2 . When the sensor  30 - 2  is exposed to a condition  114 - 2 , its current affects  288  the regulated voltage signal  286  based on I=V/Z. As such, the sensor impedance  292  corresponds to the voltage (V) provided by the regulated voltage source circuit  284  and the current flowing through the sensor  30 - 2 . As the current of the sensor  30 - 2  changes due to changing conditions  114 - 1 , the voltage provided by the regulated voltage source circuit  284  changes so that the sensor impedance  292  remains substantially equal to the impedance reference  290 , including the DC resistance and/or desired impedances at f1 and f2. 
     The voltage (V) loop correction circuit  282  is operable to generate a comparison signal  296  based on a comparison of the sensor impedance  292  with the impedance reference  290 . The effect of the current of the sensor on the regulated impedance signal  286  is detected by the V loop correction circuit  282  and is captured by the comparison signal  296 . The V loop correction circuit  282  is further operable to convert the comparison signal  296  into the digital signal  202 , which is a digital representation of the affect the current of the sensor has on the regulated voltage signal and corresponds to the sensed condition  114 - 2 . The V loop correction circuit is further operable to convert the digital signal  202  into the analog regulation signal  294 , thereby creating a feedback loop to keep the sensor impedance  292  substantially equal to the impedance reference  290 . 
       FIG.  30    is a schematic block diagram of another embodiment of a drive sense circuit  28 - f  coupled to a variable current sensor  30 - 2 . The drive sense circuit  28 - f  includes an impedance (Z) reference circuit  280 - 1 , a voltage (V) loop correction circuit  282 - 1 , and a regulated voltage (V) source circuit  284 - 1 . The Z reference circuit includes a current source circuit and an impedance (Z ref ). The V loop correction circuit  282 - 1  includes a comparator (comp), an analog to digital converter  212 - 5  and a digital to analog converter  214 - 5 . The analog to digital converter  212 - 5  and the digital to analog converter  214 - 5  are one or more of the types discussed with reference to  FIG.  23   . 
     When the drive sense circuit  28 - f   1  is enabled, the regulated voltage source circuit  284 - 1 , which includes a P-channel transistor and a voltage bias circuit, is operable to generate a regulated voltage signal  286  based on an analog regulation signal  294 . The regulated voltage source circuit  284 - 1  generates the regulated voltage signal  286  such that the sensor impedance  292  (e.g., capacitance, inductance, etc.) substantially matches the impedance reference  290  produced by the Z reference circuit  280 . 
     The Z reference circuit  280  (which includes a current source circuit and an impedance) generates the impedance reference  290  in accordance with (V/I) to include a DC component and/or at least one oscillating (AC) component. For example, the Z reference circuit generates a DC component to have a desired resistance at DC, to have a first desired impedance at frequency 1, and to have a second desired impedance at frequency 2. 
     The regulated voltage source circuit  284 - 1  provides the regulated voltage signal  286  to the sensor  30 - 2 . When the sensor  30 - 2  is exposed to a condition  114 - 2 , its current affects  288  the regulated impedance signal  286  based on I=V/Z. As such, the sensor impedance  292  corresponds to the voltage (V) provided by the regulated voltage source circuit  284  and the current flowing through the sensor  30 - 2 . As the current of the sensor  30 - 2  changes due to changing conditions  114 - 1 , the voltage provided by the regulated voltage source circuit  284  changes so that the sensor impedance  292  remains substantially equal to the impedance reference  290 , including the DC resistance and/or desired impedances at f1 and f2. 
     The comparator compares (as voltages or currents) the impedance reference with the sensor impedance  292  to produce a comparison signal  296 , which captures the effect of the current of the sensor has on the regulated impedance signal  286 . The analog to digital converter  212 - 5  converts the comparison signal  296  into the digital signal  202 , which is a digital representation of the affect the current of the sensor has on the regulated voltage signal and corresponds to the sensed condition  114 - 2 . The digital to analog converter  214 - 5  converts the digital signal  202  into the analog regulation signal  294 , thereby creating a feedback loop to keep the sensor impedance  292  substantially equal to the impedance reference  290 . 
       FIG.  30 A  is a schematic block diagram of another embodiment of a drive sense circuit  28 - f   2  coupled to a variable current sensor  30 - 2 . The drive sense circuit  28 - f   2  includes an impedance (Z) reference circuit  280 - 1 , a voltage (V) loop correction circuit  282 - 1   a,  and a regulated voltage (V) source circuit  284 - 1 . The Z reference circuit  280 - 1  includes a current source circuit and an impedance (Z ref ). The V loop correction circuit  282 - 1   a  includes a comparator (comp) and an analog to digital converter  212 - 5   a.  The analog to digital converter  212 - 5   a  is one or more of the types discussed with reference to  FIG.  23   . 
     When the drive-sense circuit  28 - f   2  is enabled, the regulated voltage source circuit  284 - 1 , which includes a P-channel transistor and a voltage bias circuit, is operable to generate a regulated voltage signal  286  based on comparison signal  296 - 1 . The regulated voltage source circuit  284 - 1  generates the regulated voltage signal  286  such that the sensor impedance  292  (e.g., capacitance, inductance, etc.) substantially matches the impedance reference  290  produced by the Z reference circuit  280 - 1 . 
     The Z reference circuit  280 - 1  (which includes a current source circuit and an impedance) generates the impedance reference  290  in accordance with (V/I) to include a DC component and/or at least one oscillating (AC) component. For example, the Z reference circuit generates a DC component to have a desired resistance at DC, to have a first desired impedance at frequency 1, and to have a second desired impedance at frequency 2. 
     The regulated voltage source circuit  284 - 1  provides the regulated voltage signal  286  to the variable current sensor  30 - 2 . When the variable current sensor  30 - 2  is exposed to a condition  114 - 2 , its current affects  288  the regulated voltage signal  286  based on I=V/Z. As such, the sensor impedance  292  corresponds to the voltage (V) provided by the regulated voltage source circuit  284 - 1  and the current flowing through the sensor  30 - 2 . As the current of the sensor  30 - 2  changes due to changing conditions  114 - 2 , the voltage provided by the regulated voltage source circuit  284  changes so that the sensor impedance  292  remains substantially equal to the impedance reference  290 , including the DC resistance and/or desired impedances at f1 and f2. 
     The comparator compares (as voltages or currents) the impedance reference  290  with the sensor impedance  292  to produce a comparison signal  296 - 1 , which captures the effect of the current of the sensor has on the regulated impedance signal  286 . The comparison signal  296 - 1  is provided to the voltage bias circuit, thereby creating a feedback loop to keep the sensor impedance  292  substantially equal to the impedance reference  290 . The analog to digital converter  212 - 5   a  converts the comparison signal  296  into the digital signal  202 , which is a digital representation of the affect the current of the sensor has on the regulated voltage signal  286  and corresponds to the sensed condition  114 - 2 . 
       FIG.  31    is a schematic block diagram of another embodiment of a drive sense circuit  28 -g coupled to a variable current sensor  30 - 2 . The drive sense circuit  28 -g includes a voltage (V) reference circuit  300 , an impedance (Z) loop correction circuit  302 , and a regulated impedance (Z) source circuit  304 . In general, the drive sense circuit  28 - g  regulates the impedance of the sensor and keeps the sensor&#39;s voltage constant to sense a current (I) of the sensor  30 - 2  in relation to a sensor voltage  306  and a voltage (V) reference  312 . Varying current of the sensor  30 - 2  is indicative of changes to the condition  114 - 2  being sensed (e.g., magnetic field, current flow, etc.), which may be used in motor monitoring applications, load sensing applications, electronic circuit applications, failure analysis applications, etc. 
     When the drive sense circuit  28 - g  is enabled, the regulated impedance source circuit  304  is operable to generate a regulated impedance signal  308  based on an analog regulation signal  314 . The regulated impedance source circuit  304  generates the regulated impedance signal  308  by varying frequency of a voltage produced by the regulated Z source circuit  304  such that the sensor voltage  306  substantially matches the voltage reference  312  produced by the V reference circuit  300 . 
     The V reference circuit  300  (which includes a bandgap reference, a linear regulator, a power supply, a divider network, an AC generator, a combining circuit and/or etc.) generates the voltage reference  312  to include a DC component and/or at least one oscillating (AC) component. For example, the V reference circuit generates a DC component to have a desired DC level, a first oscillating component at a first frequency 1, and a second oscillating component at frequency 2. Alternatively, the frequency of the oscillating component sweeps a frequency range to find a frequency, or frequencies, that optimizes the impedance of the sensor. 
     The regulated impedance source circuit  304  provides the regulated impedance signal  308  to the sensor  30 - 2 . When the sensor  30 - 2  is exposed to a condition  114 - 2 , its current affects  288  the regulated impedance signal  308  based on I=V/Z. As such, the sensor voltage  306  corresponds to the impedance of the sensor as regulated by the regulation Z source circuit and the current provided by the regulated impedance source circuit  304  to the sensor  30 - 2 . As the current of the sensor  30 - 2  changes due to changing conditions  114 - 2 , the impedance is adjusted by the regulated impedance source circuit  304  changes so that the sensor voltage  306  remains substantially equal to the voltage reference  312 , including the DC resistance and desired impedances at f1 and f2. 
     The impedance (Z) loop correction circuit  302  is operable to generate a comparison signal  316  based on a comparison of the sensor voltage  306  with the voltage reference  312 . The effect of the current of the sensor on the regulated voltage signal  308  is detected by the Z loop correction circuit  302  and is captured by the comparison signal  316 . The Z loop correction circuit  302  is further operable to convert the comparison signal  316  into the digital signal  202 , which is a digital representation of the affect the current of the sensor has on the regulated impedance signal and corresponds to the sensed condition  114 - 2 . The Z loop correction circuit is further operable to convert the digital signal  202  into the analog regulation signal  314 , thereby creating a feedback loop to keep the sensor voltage  306  substantially equal to the voltage reference  312 . 
       FIG.  32    is a schematic block diagram of another embodiment of a drive sense circuit  28 - g   1  coupled to a variable current sensor  30 - 2 . The drive sense circuit  28 - g   1  includes a voltage (V) reference circuit  300 - 1 , an impedance (Z) loop correction circuit  302 - 1 , and a regulated impedance (Z) source circuit  304 . The voltage reference circuit  300 - 1  includes a current source circuit  320  and a variable impedance. The Z loop correction circuit  302 - 1  includes a comparator or op amp, an analog to digital converter  212 - 6  and a digital to analog converter  214 - 6 . The analog to digital converter  212 - 6  and the digital to analog converter  214 - 6  are one or more of the types discussed with reference to  FIG.  23   . 
     When the drive sense circuit  28 - g   1  is enabled, the regulated impedance source circuit  304 - 1  is operable to generate the regulated impedance signal  308  based on an analog regulation signal  314 . The frequency variable bias circuit  324  provides a frequency vary gate source voltage to the P-channel FET to generate the regulated impedance signal  308 , which includes a varying frequency voltage component. In this manner, the sensor voltage  306  substantially matches the voltage reference  312  produced by the V reference circuit  300 - 1 . 
     The V reference circuit  300  (which includes a current source and a variable impedance.) generates the voltage reference  312  to include a DC component and/or at least one oscillating (AC) component. For example, the current source circuit  320  and/or the variable impedance generate a DC component to have a desired DC level, a first oscillating component at a first frequency 1, and a second oscillating component at frequency 2. Alternatively, the current source circuit  320  and/or the variable impedance performs a frequency sweeps within a frequency range to find a frequency, frequencies, that optimizes the impedance of the sensor. 
     The regulated impedance source circuit  304  provides the regulated impedance signal  308  to the sensor  30 - 2 . When the sensor  30 - 2  is exposed to a condition  114 - 2 , its current affects  288  the regulated impedance signal  308  based on I=V/Z. As such, the sensor voltage  306  corresponds to the impedance of the sensor as regulated by the regulation Z source circuit and the current provided by the regulated impedance source circuit  304  to the sensor  30 - 2 . As the current of the sensor  30 - 2  changes due to changing conditions  114 - 2 , the impedance is adjusted by the regulated impedance source circuit  304  changes so that the sensor voltage  306  remains substantially equal to the voltage reference  312 , including the DC resistance and/or desired impedances at f1 and f2. 
     The comparator is operable to generate a comparison signal  316  based on a comparison of the sensor voltage  306  with the voltage reference  312 . The effect of the current of the sensor on the regulated voltage signal  308  is detected by the Z loop correction circuit  302  and is captured by the comparison signal  316 . The analog to digital converter  212 - 6  converts the comparison signal  316  into the digital signal  202 , which is a digital representation of the affect the current of the sensor has on the regulated impedance signal and corresponds to the sensed condition  114 - 2 . The digital to analog converter  214 - 6  convert the digital signal  202  into the analog regulation signal  314 , thereby creating a feedback loop to keep the sensor voltage  306  substantially equal to the voltage reference  312 . 
       FIG.  33    is a schematic block diagram of another embodiment of a drive sense circuit  28 - g   2  coupled to a variable current sensor  30 - 2 . The drive sense circuit  28 - g   1  includes a voltage (V) reference circuit (which includes a current source and an impedance (Zref)), an impedance (Z) loop correction circuit (which includes the comparator, the analog to digital converter  212 - 6 , the digital to analog converter  214 - 6 , a current mirror circuit  322 , and a controlled variable impedance  318 ), and a regulated impedance (Z) source circuit (which includes a voltage bias circuit  324  and a P-channel FET). 
     When the drive sense circuit  28 - g   1  is enabled, the comparator compares the voltage reference signal  312  with the sensor voltage  306  to produce the comparison signal. The analog to digital converter converts the comparison signal into the digital signal  202 . The digital to analog converter converts the digital signal  202  into the analog regulation signal  314 . 
     The analog regulation signal  314  varies the impedance of the controlled variable impedance  318 . The varying impedance of circuit  318  is multiplied by the mirrored current (I m ) of the sensor current (I s ) to produce the sensor voltage  306 . The mirrored current is produced by the current mirror circuit  322  that mirrors the current provided by the P-channel FET to the variable current sensor  30 - 2 . The P-channel FET is enabled via the voltage bias circuit  324 , which includes one or more resistors and/or one or more capacitors. The varying of the impedance of the controlled variable impedance  318  regulates the sensor voltage  306  to substantially match the reference voltage  312 . 
       FIG.  34    is a schematic block diagram of another embodiment of a drive sense circuit  28 - h  coupled to a variable voltage sensor  30 - 3 . The drive sense circuit  28 - h  includes a current (I) reference circuit  330 , an impedance (Z) loop correction circuit  332 , and a regulated impedance (Z) source circuit  334 . In general, the drive sense circuit  28 - h  regulates the impedance of the sensor and keeps the sensor&#39;s current constant to sense a voltage (V) of the sensor  30 - 3  in relation to a sensor current  336  and a current (I) reference  342 . Varying voltage of the sensor  30 - 3  is indicative of changes to the condition  114 - 3  being sensed (e.g., voltage levels, capacitance, inductance, thermal conditions, etc.). 
     When the drive sense circuit  28 - h  is enabled, the regulated impedance source circuit  334  is operable to generate a regulated impedance signal  338  based on an analog regulation signal  344 . The regulated impedance source circuit  334  generates the regulated impedance signal  338  by varying frequency of a current produced by the regulated Z source circuit  334  such that the sensor current  306  substantially matches the voltage reference  342  produced by the I reference circuit  330 . 
     The I reference circuit  330  (which may be implement in accordance with a previously discussed current reference circuit) generates the current reference  342  to include a DC component and/or at least one oscillating (AC) component. For example, the I reference circuit generates a DC component to have a desired DC level, a first oscillating component at a first frequency 1, and a second oscillating component at frequency 2. Alternatively, the frequency of the oscillating component sweeps a frequency range to find a frequency, or frequencies, that optimizes the impedance of the sensor. 
     The regulated impedance source circuit  334  provides the regulated impedance signal  338  to the sensor  30 - 3 . When the sensor  30 - 3  is exposed to a condition  114 - 3 , its voltage affects  288  the regulated impedance signal  338  based on V=I*Z. As such, the sensor current  336  corresponds to the impedance of the sensor as regulated by the regulation Z source circuit and the voltage provided by the regulated impedance source circuit  334  to the sensor  30 - 3 . As the voltage of the sensor  30 - 3  changes due to changing conditions  114 - 3 , the impedance is adjusted by the regulated impedance source circuit  334  so that the sensor current  336  remains substantially equal to the current reference  342 , including the DC resistance and/or desired impedances at f1 and f2. 
     The impedance (Z) loop correction circuit  332  is operable to generate a comparison signal  346  based on a comparison of the sensor current  336  with the current reference  342 . The effect of the voltage of the sensor on the regulated impedance signal  338  is detected by the Z loop correction circuit  332  and is captured by the comparison signal  336 . The Z loop correction circuit  332  is further operable to convert the comparison signal  336  into the digital signal  202 , which is a digital representation of the affect the voltage of the sensor has on the regulated impedance signal and corresponds to the sensed condition  114 - 3 . The Z loop correction circuit is further operable to convert the digital signal  202  into the analog regulation signal  344 , thereby creating a feedback loop to keep the sensor current  336  substantially equal to the current reference  342 . 
       FIG.  35    is a schematic block diagram of another embodiment of a drive sense circuit  28 - h   1  coupled to a variable voltage sensor  30 - 3 . The drive sense circuit  28 - h   1  includes a current (I) reference circuit  330 , an impedance (Z) loop correction circuit  332 , and a regulated impedance (Z) source circuit  334 . The I reference circuit  330  includes a variable current source circuit  350 . The Z loop correction circuit  332  includes a comparator, an analog to digital converter  212 - 8  and a digital to analog converter  214 - 8 . The regulated Z source circuit  334  includes a variable impedance  354 , a P-channel FET, and a voltage bias circuit  352 . The analog to digital converter  212 - 8  and the digital to analog converter  214 - 8  are one or more of the types discussed with reference to  FIG.  23   . 
     The voltage bias circuit  352  generates a gate-source voltage for the P-channel FET and the impedance of the variable impedance is adjusted based on the analog regulation signal  344 . In this embodiment, the combination of the variable impedance and P-channel transistor generate a regulated impedance signal  338  at a desired current level for the variable voltage sensor  30 - 3 . The regulated impedance signal  338  is regulated to obtain a desired impedance of the sensor  30 - 3  such that, at the desired current level (e.g., a few micro amps to an amp or more), variation of the voltage of the sensor is within the linear range of the sensor. 
     The I reference circuit  330  (which may be implement in accordance with a previously discussed current reference circuit) generates the current reference  342  to include a DC component and/or at least one oscillating (AC) component. For example, the variable current source circuit  350  generates a DC component to have a desired DC level, a first oscillating component at a first frequency 1, and a second oscillating component at frequency 2. 
     The comparator (e.g., a transimpedance amplifier) compares the sensor current  336  with the current reference  342  to produce the comparison signal  346 . The effect of the voltage of the sensor on the regulated impedance signal  338  is captured by the comparison signal  336 . The analog to digital converter  212 - 8  converts the comparison signal  346  into the digital signal  202 , which is a digital representation of the affect the voltage of the sensor has on the regulated impedance signal and corresponds to the sensed condition  114 - 3 . The digital to analog converter converts the digital signal  202  into the analog regulation signal  344 , thereby creating a feedback loop to keep the sensor current  336  substantially equal to the current reference  342 . 
       FIG.  36    is a schematic block diagram of another embodiment of a drive sense circuit  28 - h   2  is coupled to a variable voltage sensor  30 - 3 . The drive sense circuit  28 - h   2  includes a P-channel transistor  335 , a variable impedance  333  (e.g., resistor(s), capacitor(s), and/or transistor(s)), a comparator  331 , the analog to digital converter  212 - 8 , and the digital to analog converter  214 - 8 . 
     In operation, the variable voltage sensor  30 - 3  is exposed to a condition that changes its voltage when its receiving the variable impedance signal at a current level (I s ). The comparator  331  compares a mirrored current of the sensor  30 - 1  with the current reference  342  to produce the comparison signal  336 . The analog to digital converter  212 - 8  converts the comparison signal  336  into the digital signal  202 . The digital to analog converter  214 - 8  convers the digital signal  202  into the analog regulation signal  344 . The variable impedance  333  is adjusted based on the analog regulation signal  334 . Adjusting the variable impedance  333  adjusts the gate-source voltage of the P-channel transistor to produce the regulated impedance signal  338 . 
       FIG.  37    is a schematic block diagram of another embodiment of a drive sense circuit  28 - i  coupled to a variable voltage sensor  30 - 3 . The drive sense circuit  28 - i  includes an impedance (Z) reference circuit  360 , a current (I) loop correction circuit  262 , and a regulated current (I) source circuit  264 . In general, the drive sense circuit  28 - i  regulates the current applied to the sensor and keeps the impedance of sensor constant to sense a voltage of the sensor  30 - 3  in relation to a sensor impedance  366  and an impedance reference  372 . 
     When the drive sense circuit  28 - i  is enabled, the regulated current source circuit  364  is operable to generate a regulated current signal  368  based on an analog regulation signal  374 . The regulated current source circuit  364  generates the regulated current signal  368  such that the sensor impedance (Z)  366  substantially matches the impedance reference  372  produced by the Z reference circuit  260 . 
     The Z reference circuit  360  (which may be a capacitor, an inductor, a circuit equivalent of a capacitor, a circuit equivalent of an inductor, a tunable capacitor bank, etc.) generates the impedance reference  372  to include a DC component and/or at least one oscillating component. For example, the impedance reference  372  includes a DC component and/or at least one oscillating (AC) component. For example, the Z reference circuit  360  generates a DC component to have a desired resistance at DC, a first desired impedance at frequency 1, and a second desired impedance at frequency 2. 
     The regulated current source circuit  364  provides the regulated current signal  368  to the sensor  30 - 3 . When the sensor  30 - 3  is exposed to a condition  114 - 3 , its voltage affects  370  the regulated current signal  388  based on I=V/Z. As such, the sensor impedance  366  is created as a result of the current (I) provided by the regulated current source circuit  364  and the voltage of the sensor  30 - 3 . As the voltage of the sensor  30 - 3  changes due to changing conditions  114 - 3 , the current provided by the regulated current source circuit  234  changes so that the sensor impedance  366  remains substantially equal to the impedance reference  372 , including the DC component and/or the oscillating component(s). 
     The current (I) loop correction circuit  362  is operable to generate a comparison signal  376  based on a comparison of the sensor impedance  366  with the impedance reference  372 . The effect of the voltage of the sensor on the regulated current signal  368  is detected by the I loop correction circuit  362  and captured by the comparison signal  376 . The I loop correction circuit  362  is further operable to convert the comparison signal  376  into a digital signal  202 , which is a digital representation of the affect the voltage of the sensor has on the regulated current signal and corresponds to the sensed condition  114 - 3 . The I loop correction circuit is further operable to convert the digital signal  202  into the analog regulation signal  374 , thereby creating a feedback loop to keep the sensor impedance  366  substantially equal to the impedance reference  372 . 
       FIG.  38    is a schematic block diagram of another embodiment of a drive sense circuit  28 - i   1  coupled to a variable voltage sensor  30 - 3 . The drive sense circuit  28 - i   1  includes an impedance (Z) reference circuit  360 - 1 , a current (I) loop correction circuit  262 - 1 , and a regulated current (I) source circuit  364 - 1 , implemented as a dependent current source. The Z reference circuit  360 - 1  includes a current source circuit and an impedance circuit (e.g., resistor(s), capacitor(s), inductor(s), transistor(s), etc.) to produce the impedance reference, which may be expressed as a voltage (V of impedance reference=current of current source times impedance of the impedance circuit). 
     The dependent current source  364 - 1  generate a regulated current signal  368  based on the analog regulation signal  374 . The voltage of the sensor  30  and current of the regulated current signal  368  provides the sensor impedance  366 . 
     The comparator compares the sensor impedance  366  with the impedance reference, which may be done in voltage, to produce the comparison signal  376 . The analog to digital converter  212 - 8  converts the comparison signal  376  into a digital signal  202 , which is a digital representation of the affect the voltage of the sensor has on the regulated current signal and corresponds to the sensed condition  114 - 3 . The digital to analog converter  214 - 8  converts the digital signal  202  into the analog regulation signal  374 , thereby creating a feedback loop to keep the sensor impedance  366  substantially equal to the impedance reference  372 . 
     As used in the preceding figures, a drive sense circuit has the general reference number of 28. When, in a particular figure, the drive sense circuit&#39;s reference number has a suffix (e.g., -a, -b, -c, etc.), the reference number with a suffix is referring to a specific embodiment of a drive sense circuit. A specific embodiment of a drive sense circuit includes some or all of the features and/or functions of drive sense circuits having no suffix to its reference number. Further, when a drive sense circuit has a suffix with a letter and a number, this is represented of different sub-embodiments of an embodiment of the drive sense circuit. The same applies for other components in the figures that have a reference number with a suffix. 
     It is noted that terminologies as may be used herein such as bit stream, stream, signal sequence, etc. (or their equivalents) have been used interchangeably to describe digital information whose content corresponds to any of a number of desired types (e.g., data, video, speech, text, graphics, audio, etc. any of which may generally be referred to as ‘data’). 
     As may be used herein, the terms “substantially” and “approximately” provide an industry-accepted tolerance for its corresponding term and/or relativity between items. For some industries, an industry-accepted tolerance is less than one percent and, for other industries, the industry-accepted tolerance is 10 percent or more. Other examples of industry-accepted tolerance range from less than one percent to fifty percent. Industry-accepted tolerances correspond to, but are not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, thermal noise, dimensions, signaling errors, dropped packets, temperatures, pressures, material compositions, and/or performance metrics. Within an industry, tolerance variances of accepted tolerances may be more or less than a percentage level (e.g., dimension tolerance of less than +/−1%). Some relativity between items may range from a difference of less than a percentage level to a few percent. Other relativity between items may range from a difference of a few percent to magnitude of differences. 
     As may also be used herein, the term(s) “configured to”, “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for an example of indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. 
     As may even further be used herein, the term “configured to”, “operable to”, “coupled to”, or “operably coupled to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform, when activated, one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item. 
     As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal  1  has a greater magnitude than signal  2 , a favorable comparison may be achieved when the magnitude of signal  1  is greater than that of signal  2  or when the magnitude of signal  2  is less than that of signal  1 . As may be used herein, the term “compares unfavorably”, indicates that a comparison between two or more items, signals, etc., fails to provide the desired relationship. 
     As may be used herein, one or more claims may include, in a specific form of this generic form, the phrase “at least one of a, b, and c” or of this generic form “at least one of a, b, or c”, with more or less elements than “a”, “b”, and “c”. In either phrasing, the phrases are to be interpreted identically. In particular, “at least one of a, b, and c” is equivalent to “at least one of a, b, or c” and shall mean a, b, and/or c. As an example, it means: “a” only, “b” only, “c” only, “a” and “b”, “a” and “c”, “b” and “c”, and/or “a”, “b”, and “c”. 
     As may also be used herein, the terms “processing module”, “processing circuit”, “processor”, “processing circuitry”, and/or “processing unit” may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module, module, processing circuit, processing circuitry, and/or processing unit may be, or further include, memory and/or an integrated memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of another processing module, module, processing circuit, processing circuitry, and/or processing unit. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, module, processing circuit, processing circuitry, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that if the processing module, module, processing circuit, processing circuitry and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element may store, and the processing module, module, processing circuit, processing circuitry and/or processing unit executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the Figures. Such a memory device or memory element can be included in an article of manufacture. 
     One or more embodiments have been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claims. Further, the boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality. 
     To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claims. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof. 
     In addition, a flow diagram may include a “start” and/or “continue” indication. The “start” and “continue” indications reflect that the steps presented can optionally be incorporated in or otherwise used in conjunction with one or more other routines. In addition, a flow diagram may include an “end” and/or “continue” indication. The “end” and/or “continue” indications reflect that the steps presented can end as described and shown or optionally be incorporated in or otherwise used in conjunction with one or more other routines. In this context, “start” indicates the beginning of the first step presented and may be preceded by other activities not specifically shown. Further, the “continue” indication reflects that the steps presented may be performed multiple times and/or may be succeeded by other activities not specifically shown. Further, while a flow diagram indicates a particular ordering of steps, other orderings are likewise possible provided that the principles of causality are maintained. 
     The one or more embodiments are used herein to illustrate one or more aspects, one or more features, one or more concepts, and/or one or more examples. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones. 
     While the transistors in the above described figure(s) is/are shown as field effect transistors (FETs), as one of ordinary skill in the art will appreciate, the transistors may be implemented using any type of transistor structure including, but not limited to, bipolar, metal oxide semiconductor field effect transistors (MOSFET), N-well transistors, P-well transistors, enhancement mode, depletion mode, and zero voltage threshold (VT) transistors. 
     Unless specifically stated to the contra, signals to, from, and/or between elements in a figure of any of the figures presented herein may be analog or digital, continuous time or discrete time, and single-ended or differential. For instance, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more particular architectures are described herein, other architectures can likewise be implemented that use one or more data buses not expressly shown, direct connectivity between elements, and/or indirect coupling between other elements as recognized by one of average skill in the art. 
     The term “module” is used in the description of one or more of the embodiments. A module implements one or more functions via a device such as a processor or other processing device or other hardware that may include or operate in association with a memory that stores operational instructions. A module may operate independently and/or in conjunction with software and/or firmware. As also used herein, a module may contain one or more sub-modules, each of which may be one or more modules. 
     As may further be used herein, a computer readable memory includes one or more memory elements. A memory element may be a separate memory device, multiple memory devices, or a set of memory locations within a memory device. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. The memory device may be in a form a solid-state memory, a hard drive memory, cloud memory, thumb drive, server memory, computing device memory, and/or other physical medium for storing digital information. 
     While particular combinations of various functions and features of the one or more embodiments have been expressly described herein, other combinations of these features and functions are likewise possible. The present disclosure is not limited by the particular examples disclosed herein and expressly incorporates these other combinations.