Patent Description:
Sensors are devices that transpose the events from the physical world into electrical signals suitable for further processing, which ultimately ends by providing useful information to the user. The conditioning and processing of the electrical signal from the sensor is a crucial part of obtaining the information provided by the sensor, since these signals can be quite small and can be easily corrupted due to today's environment with many sources of interference such as electronic devices, cars, and mobile phones. The analog or digital output of many different sensors can be voltage or current driven with different ranges, for example, from -500V to +500V, -10Amps to +10Amps and a wide range of frequencies from <NUM> to several Ghz. With regard to complexity of the output electronics of the sensors, at one end of the scale there are sensors comprising an amplifier with a filter. At the other end there are sensors having a full signal conditioning front end, intermediate analog signal processing, an ADC, perhaps a microcontroller unit (MCU), and sometimes even more functionality.

Smart mobile communication devices are essentially small computers that most of the time are connected to the internet and are carried by consumers. They include, for example, commercially-available smartphones and mobile devices such as an IPOD, MP4, tablets with Apple IOS, Microsoft Windows or Google Android operating systems, devices with wireless communication capabilities such as WI-FI, LTE, <NUM>, <NUM>, or newer generation capabilities. For the sake of brevity, any existing smart mobile communication devices and any similar device that will be developed in the future devices will be referred to hereinafter cumulatively as a "smart device".

Smart devices are being developed constantly and new ways to make them useful are constantly being presented to users. One useful addition to these smart devices would be a way to connect external sensors to the device and then to make use of a downloaded or installed software application in the smart device or the sensor to display the output of the sensor on the screen of the smart device. However, since the range of readings for different sensors is significantly large, it is difficult to connect them directly to the smart device for reading or for providing the useful information.

<CIT> discloses a generic transducer interface that is connected via a wired or wireless path to communicate with an external host computer. Transducer specific configuration data is sent from the host computer to configure control components of the interface with information needed to act as an interface for a particular transducer.

<CIT> discloses a frontend comprising what is called dynamically configurable analog frontend circuitry. The frontend comprises inputs for several sensors including separate inputs for sensors having voltage outputs and sensors having current outputs. The electronic components of the frontend are arranged in a fixed circuit that is suitable for a variety of connected sensors. The frontend is not configured by rearrangement of circuit elements to create new circuits for each sensor that is attached to it. Instead the operating parameters of components in the circuit can be adjusted as needed to deal with signals from different sensors and combinations of sensors.

<CIT> discloses a semiconductor device comprising a configurable analog front end (AFE) and a control unit. When an analog sensor is connected to the AFE the control unit changes the configuration and operating characteristics of components on the AFE to allow digitization of signals from the sensor.

It is a purpose of the present invention to provide a simple setup that bridges the gap between an external sensor and a smart device.

Further purposes and advantages of this invention will appear as the description proceeds.

The invention relates to a smart device and an associated Analog Front End (AFE) as defined by the appended claims.

Disclosed herein is a smart device comprising a configurable internal analog front end [AFE], a software application, and at least one port through which the output of an external sensor that transmits and/or receives data can be connected to the AFE. The smart device comprises the following features:.

The smart device is characterized in that connection of an external sensor to the configurable AFE initiates execution of the software application on the smart device, wherein the application is programmed to: (i) identify the type of the external sensor, (ii) select appropriate components of the configurable AFE, and (iii) to arrange connections between them to form an AFE circuit suitable for the external sensor.

Examples of the smart device comprise a dedicated port and a general-purpose protocol that describes ranges of at least one of voltage, current, duty cycle, and synchronization, wherein different types of external sensors that are adapted to meet this protocol can be connected to the configurable AFE through the dedicated port.

In examples of the smart device the configurable AFE is programmed via one of the following bus protocols: parallel, Serial Peripheral Interface (SPI), Universal Serial Bus, and Inter-Integrated Circuit (I2C).

In examples of the smart device the configurable AFE of the smart device is configured to either receive signals from a one-way sensor or receive signals from and send signals to a two-way sensor or both receive signals from a one-way sensor and receive signals from and send signals to a two-way sensor.

In examples of the smart device the one way sensors are chosen from the group comprising: audio sensors, heat sensors, temperature sensors, electrochemical sensors, and light sensors, and the two-way sensor is an ultrasound sensor.

In examples of the smart device the configurable AFE comprises an ADC having a sampling rate with a known fixed frequency of <NUM>, wherein any input signal from an ultrasound transducer having a maximum frequency of <NUM> that is connected to the AFE will have less than half of this known fixed frequency.

In examples of the smart device the configurable AFE comprises an ADC with a sampling rate that can be tuned to be at least <NUM>, which is twice the frequency of the signals from an ultrasound transducer having a maximum frequency of <NUM> that is connected to the AFE.

In examples of the smart device data read from an external sensor is processed by the configurable AFE that is an integral part of the application processor and then displayed on a screen of the smart device.

In examples of the smart device some of the functions that could be carried out by hardware components of the configurable AFE are implemented by software in the application processor.

All the above and other characteristics and advantages of the disclosure will be further understood through the following illustrative and non-limitative description of examples thereof, with reference to the appended drawings.

Disclosed is a smart device and an associated Analog Front End (AFE)that enables connection of a wide variety of sensors to a smart device and, with the aid of a suitable software application or application processor, allows the sensor acquired information to be displayed on the smart device. Two basic examples of the AFE will be described - an external unit that is connected to the smart device via one of the existing ports and an internal unit that in some cases utilizes some of the existing components of the device.

In order to illustrate the disclosure a smartphone has been chosen as a representative smart device. However it is to be understood that the disclosure can be adapted mutatis mutandis to couple any smart device, whether presently available or developed in the future, to external sensors in the same manner as discussed herein with respect to smartphones.

<FIG> is a block diagram that shows the basic physical components of a smartphone. This diagram is very simplified and basically only shows the phone function but it is sufficient for purposes of understanding the disclosure.

Radio section <NUM> comprises a transmit circuit, which sends signals via power amplifier circuit <NUM> and bandpass filter switch <NUM> to antenna <NUM> that broadcasts them to the smartphone of another user. Radio section <NUM> also comprises a receive circuit that receives signals gathered by antenna <NUM> and filtered by bandpass filter switch <NUM>.

Analog Baseband section <NUM> comprises circuits for converting and processing analog to digital and digital to analog signals, power management circuits including power distribution circuits that distribute power from a battery to other circuits in the phone and a circuit based on charging circuit <NUM> that takes power from an external source and uses it to charge the battery of the smartphone. Analog Baseband section <NUM> also comprises an Audio Codecs section that handles and processes analog and digital audio signals from a microphone <NUM> and to speakers <NUM> or headset <NUM>.

The Digital Baseband section <NUM> comprises a microcontroller unit (MCU) <NUM> responsible for controlling the various functions of the device and memory circuits as well as a peripherals section <NUM> that comprises interfaces for connecting devices and services such as Wi-Fi, camera, and USB.

In order to implement the disclosure an analog front end (AFE) that serves as the interface between sensor/input analog signals and an Analog to Digital Converter (ADC) used to convert the sensor signals to those that can be handled by the smart device must be provided.

<FIG> symbolically shows the system of the major components of the disclosure. Seen in the figure is a configurable analog front end (AFE) <NUM> that receives output signals from an external sensor <NUM>. The function of the ADC is to adapt the signals from the sensor to ensure that they will be digitized under optimal conditions or agreed protocol that can enter the smartphone via the peripherals section <NUM> and then be handled by the MCU <NUM> and a software application on the smartphone to be processed, stored, and displayed like any other input to the device. Herein the MCU that deals with external sensor functions will be designated application processor <NUM>.

The basic idea of the disclosure is to provide a smart device comprising a configurable AFE that is comprised of a collection of many components (amplifiers, mixers, filters, analog-to-digital converter (ADC), etc.) that could be needed to form an AFE for several different types of sensors (or at least a given list of several different types of sensor). Connection of a sensor to the configurable AFE initiates execution of an application on the smart device that is programmed to select the appropriate components and to arrange connections between them to form an AFE circuit suitable for that sensor. The configurable AFE can be provided with default settings that allow connection of certain types of sensor without the necessity of reconfiguring the AFE whenever one of these types of sensors is connected to it.

The configurable AFE of the disclosure can be designed as one or more components that can be implemented with ASIC or as several individual components that include one or more amplifiers, or a programmable amplifier for which each stage can be programmed so that the circuit can be changed to match the requirements of different sensors, different analog to digital converter (ADC), electrical circuits, etc. In addition, the AFE can be a single channel AFE or a multi-channel (<NUM> to N channels) AFE, with or without multiplexers, that provides not only AFE but other services as well. The configurable AFE can be designed to be one-way, i.e. to only receive signals from a sensor, or two-way, i.e. to receive signals from a sensor and also to send signals to the sensor.

The configurable AFE of the disclosure can be programmed via different bus protocols, for example, parallel or Serial Peripheral Interface (SPI) bus (a synchronous serial communication interface), Universal Serial Bus or I<NUM>C (Inter-Integrated Circuit), which is a multi-master, multi-slave, single-ended, serial computer bus; however, other agreed protocols can be used.

In examples of the disclosure some of the functions of hardware components of the configurable AFE, e.g. filtering, or amplification can be implemented by software that is related to the application processor.

There are two ways in which the disclosure can be implemented. The first way, which is useful for understanding the disclosure, is to connect the sensor to an external AFE component that is connected through one of the existing ports - for example, the audio, USB, Bluetooth or wireless ports - to the smartphone, or to a new port that is dedicated to the external sensor application. The second way to implement the disclosure is to provide the AFE as an internal component of the smartphone and to allow the sensor to connect to the AFE through any of the standard ports on the smartphone - for example, the audio, USB, MIPI, Bluetooth or wireless ports or via a new port dedicated for sensors.

Examples of the disclosure in which the AFE is an internal component have a great advantage over examples having an external AFE, since the AFE is part of the integrated circuits (ICs) of the smartphone. In this case, if a dedicated port is provided, a suitable, general-purpose protocol that describes the ranges of voltage, current, duty cycle, and synchronization is provided and any external sensor will be adapted to meet this protocol. This shortens the integration time since for a known protocol the application software will have to deal with known parameters. Obviously in order to reduce risks to the other IC components in the smartphone, it is possible to isolate this IC from others or if there is a good confidence level that this IC cannot harm other components, then it is possible to combine it with other components to reduce the cost of the product.

The main building blocks commonly found in analog front ends and that are therefore found in examples of the configurable AFE <NUM> of the smart device of the disclosure are illustrated in <FIG>. Implementation of an AFE <NUM> for a specific sensor is very application dependent and consists of different instances of the blocks shown in <FIG> combined to provide an optimal match between the input signals from the sensor and the ADCs. If however, an agreed AFE component is implemented in a smartphone for example, with a protocol that describes how to interface, then there might be a significant number of sensors that can use this AFE to directly interface to the smartphone or additional building blocks can be added as described above to adapt a specific sensor to the existing AFE in the smart phone.

In addition the disclosure is able to accommodate two types of sensors. The first type is a one-way sensor, i.e. a sensor that measures a specific parameter and sends the measurement through the AFE to the display. The second type of sensor can act in two ways, i.e. send results through the AFE but also can receive instruction or activity. Examples of the first type are heat measurement sensors, speakers, and microphones. An example of the second type is an ultrasound probe that sends energy but also can collect energy. The second type can also be defined as dual sensor since it does two activities or more.

Referring to <FIG>, exciting signals <NUM> are picked up by sensor <NUM>. The analog output of sensor <NUM> passes through an isolation stage <NUM>, which is sometimes required to ensure that the sensor/signal is isolated from the rest of the acquisition system, and that there isn't any direct electrical connection between them. The isolation stage usually consists of a simple transformer, but can also be implemented using an active isolation amplifier if the bandwidth of the signal is relatively small. After the isolation stage <NUM> the signal progresses to one or more amplifier stages <NUM>. Following the amplification stage <NUM> the signal passes to a mixer stage <NUM> where the frequency of a signal is shifted up or down by multiplying it with a sine wave signal generated by a local oscillator <NUM>. A filter <NUM> is typically used to remove unwanted frequency components resulting from the multiplication process.

Examples of the AFE <NUM> can comprise several amplifiers and mixers with different characteristics as well as more than one filter to remove unwanted frequency components from the signal at strategic locations. In addition to the isolation stage, which is not needed in some examples, the AFE can comprise an output driver <NUM>. In the example shown in <FIG>, the original signals <NUM> received by the sensor <NUM> having been optimized by the components of the AFE <NUM> then pass through ADC <NUM> to the application processor <NUM> of the smart phone. In the present disclosure the ADC <NUM> is an integral component of the AFE <NUM>.

Regarding the ADC, there are two options that can be considered when designing the configurable AFE of the disclosure. The options are related to the Nyquist sampling theorem that states that for a given signal with a certain frequency, the ADC must sample at least at double that frequency in order to maintain the information. Thus, the two options are: a. provide an ADC having a sampling rate with a known fixed frequency that is high enough such that any input signal from a sensor will have less than half of this frequency; b. provide an ADC with a sampling rate that can be tuned to be at least twice the frequency of the signals from a specific sensor that is connected to the AFE.

In an example of the disclosure (discussed further with respect to example <NUM> herein below) the hardware components of the AFE can be integrated with the application processor in a single ASIC, which is in turn connected to a port for receiving an analog sensor signal. When a sensor is connected to the port, software in the application processor identifies the type of sensor and configures the AFE accordingly.

The goal of the disclosure is to enable both ordinary users and professionals in specialized fields to connect any type of sensor to a smart device in order to measure phenomenon that are of interest to them.

Amongst other advantages, use of the system of the disclosure could save considerable cost since users are only required to purchase the sensing element itself without the housing, additional circuitry, and display screen of purchasing typically expensive dedicated sensing instruments. Once the analog output from the sensor enters the peripherals section of the smart device via an appropriately configured AFE, then software installed on the smart device is able to process and interpret the digital signals and the circuitry of the smart device is able to display the results on the screen, to save them in memory, or to send them to remote locations by any of the methods commonly available to smart device users, e.g. voice message, internet, email, and SMS.

Now will be described some examples of AFE's that can be created for specific sensors by assembling only some of the available components on the configurable AFE of the disclosure.

<FIG> schematically shows an example of an analog front end that could be used with the disclosure. In this case the signal <NUM> present at the input of the AFE, is an audio signal <NUM> and the sensor <NUM> is a radio receiver. The input signal, which is accompanied by an undesired interfering signal, is buffered by amplifier stage <NUM> to bring it to an optimal level for the following mixer stage <NUM>. The mixer stage <NUM> uses input from local oscillator <NUM> to create two copies of the input signal: one shifted down (and inverted) in frequency, and another one shifted up in frequency. Then a filter stage <NUM> removes all unwanted components. Finally, an output driver (amplifier stage) <NUM> brings the amplitude of the signal to an optimal level to drive the ADC <NUM>. Finally the digitized signal <NUM> passes to the application processor <NUM> (see <FIG>) in the smart device. The AFE shown in <FIG> typically operates using input signals having voltages of <NUM> to <NUM>.

Temperature sensors are adapted to be used in many applications such as measuring the environment temperature, human body temperatures, and water temperature. They can use a simple AFE connected to the audio or USB input of a smartphone. The AFE will amplify and digitize the readings and these results will be read by an application in the smartphone and presented on the screen or transmitted to other address.

This application requires a very simple and basic AFE, whose basic building blocks are schematically illustrated in <FIG>. An instrumentation amplifier <NUM> amplifies the output signals <NUM> from the sensor, e.g. a thermistor or thermopile (not shown in the figure), and passes the amplified signals to a filter <NUM> that is implemented with several stages to eliminate unwanted frequencies and improve the signal to noise ratio. A variable gain amplifier <NUM> amplifies the filtered signal for the ADC <NUM>. Finally the digitized signal <NUM> passes to the application processor <NUM> (see <FIG>) in the smart device.

An ultrasound transducer has a relative large range of exciting voltage and frequencies (or differences in time delay to excite the transducer elements). In this case, a programmable AFE that enables the designer to configure internally the application (in the smartphone) will provide the necessary setup for the ranges of voltage amplitudes and current as well as the frequency range, low noise amplifiers amplify the received echoes (between a few hertz to <NUM>), making it possible to integrate a time gate circuit to control the different signals and to enable an analog to digital converter to produce a stream of bits from the received echo.

A schematic diagram showing the main components in a suitable AFE for the receiving circuit of an ultrasound transducer is shown in <FIG>. The AFE comprises low-noise amplifier <NUM>, variable gain amplifier <NUM>, anti-alias filter <NUM>, and ADC <NUM>. Signals <NUM> from each element of a transmitter/receiver transducer pass through a transmit/receive switch <NUM> that protects the low-noise amplifier from the high voltage transmit signals sent to the transducer. Low-noise amplifier <NUM> provides an initial fixed gain to optimize the receiver's noise performance. The amplified receive signals then pass to variable gain amplifier <NUM>, which compensates for the attenuation of the ultrasound signals to reduce the dynamic range requirements for the subsequent ADC. Anti-alias filter <NUM> removes highfrequency noise beyond the normal maximum imaging frequencies preventing them from being mapped into the receive band by the ADC <NUM>. The amplified and digitized image data signals <NUM> from the transducer elements can be sent for example to the application processor of the smart device where they are delayed and summed by the ultrasound software loaded in the smart device to generate a focused receive beam formed signal. The resulting digital signal is used to generate 2D images.

<FIG> schematically shows the main components of an AFE for use with a three-lead electrochemical sensor <NUM>, for example for measuring CO<NUM> concentration. In this example AFE <NUM> comprises a bias circuit comprised of reference voltage <NUM> and control amplifier <NUM> to maintain the sensor at a specific state that is settable by the user. The output from sensor <NUM> is a current, which is converted by trans-impedance amplifier <NUM> to a voltage that is fed to ADC <NUM>. The output <NUM> from the ADC is transferred to application processor <NUM> of the smart device where it is converted into values of the concentration by dedicate software on the smart device.

Ambient light is the surrounding environmental light that is everywhere - equally intense and with no directionality. Even though the light is equally intense, the brightness can vary greatly. "Lux" is the amount of visible light illuminating a point on a surface. Ambient light sensors are photo detectors that are designed to sense as accurately as possible what the human eye perceives.

The AFE for this application is extremely simple and is shown schematically in <FIG>. In this case the output of photo detector <NUM> is amplified by amplifier <NUM> and the output of the amplifier is fed directly to ADC <NUM>. The output <NUM> from the ADC <NUM> is transferred to the application processor of the smart device where it is converted into values of the lux by dedicated software on the smart device.

An extended example of the system of the disclosure in which the AFE is an internal component is a highly integrated analog front-end (AFE) that is similar to a System on Chip (SoC) that also includes transmitter, receiver, and switches to change position during transmission of high voltage signals and even a field programmable gate array (FPGA) or microcontroller. In this example the hardware components of the AFE can be integrated with the application processor in a single ASIC. Such an internal component or SoC can bridge the gap to many electromagnetic and acoustic sensors and can easily connect them to the smartphone through the existing ports or a through a special dedicated port.

<FIG> schematically shows a programmable AFE <NUM> that is created on a single substrate <NUM> together with components of the smart device. In the specific example shown in <FIG> the sensor is an infrared thermometer, which is widely used to measure object or patient temperature without contact. An Infrared thermometer uses a thermopile sensor to measure temperature. Thermopile sensor <NUM> has an IR absorber which is connected to a series of thermocouples which measure the object's temperature. The ambient temperature of the sensor <NUM> is measured using a thermistor to compensate the reading of the thermopile to arrive at the final object temperature.

Usually the output of a thermopile, which is in the order of a few µV is amplified by programmable gain amplifier (PGA) 90a. Using Correlated Double Sampling the output can be amplified while reducing undesired offset and low frequency noise. An Infinite Impulse Response (IIR) filter (not shown in the figure) can be used to reduce high frequency noise. Also the output of a thermistor is amplified by PGA 90b to measure the resistance of the thermistor from which the ambient temperature can be measured.

The outputs from PGA 90a and PGA 90b are passed to via multiplexer <NUM> to ADC <NUM> and then the output <NUM> of the ADC is passed to the application processor <NUM> of the smart device where temperature of the object is calculated from the readings from the thermopile and the thermistor.

All of the remaining elements shown on the substrate <NUM> are electronic circuits of the smart device including: charging circuit <NUM> that distributes electric energy from battery <NUM> to the other components; real time clock circuit <NUM>; mechanical or touch sensing circuit <NUM> that interfaces between the application processor <NUM> and real or virtual input keys used by the user to carry out the phone functions or to program the PGA's; an LCD driver circuit <NUM> used to send information to the LCD display of the smart device; and an audio input/output circuit <NUM> connected to a speaker, headphones, or microphone of the smart device.

Claim 1:
A smart device comprising a configurable internal analog front end [AFE] (<NUM>,<NUM>), a software application, and at least one port (<NUM>,<NUM>,<NUM>) through which the output of an external sensor (<NUM>,<NUM>,<NUM>,<NUM>) that transmits and/or receives data can be connected to the AFE (<NUM>,<NUM>), wherein:
a) the smart device is a mobile communication device, which is a small computer that is adapted to be connected to the internet and to be carried by a consumer;
b) components of the configurable AFE (<NUM>,<NUM>) are configurable to digitize the signals (<NUM>) from different types of external sensors (<NUM>,<NUM>,<NUM>,<NUM>);
c) the AFE (<NUM>,<NUM>) is an internal component of the smart device and at least some of the hardware components (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,90a,90b,<NUM>) of the AFE (<NUM>,<NUM>) are integrated with the application processor (<NUM>) of the smart device in a single application-specific integrated circuit [ASIC];
the smart device characterized in that connection of an external sensor (<NUM>,<NUM>,<NUM>,<NUM>) to the configurable AFE (<NUM>,<NUM>) initiates execution of the software application on the smart device, wherein the application is programmed to: (i) identify the type of the external sensor (<NUM>,<NUM>,<NUM>,<NUM>), (ii) select appropriate components (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,90a,90b,<NUM>) of the configurable AFE (<NUM>,<NUM>), and (iii) to arrange connections between them to form an AFE circuit suitable for the external sensor (<NUM>,<NUM>,<NUM>,<NUM>).