Patent Publication Number: US-2023156374-A1

Title: Handheld communication device with drive-sense imaging array and methods for use therewith

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     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. 17/444,955, entitled “HANDHELD COMMUNICATION DEVICE WITH DRIVE-SENSE CIRCUIT BASED IMAGING ARRAY AND METHODS FOR USE THEREWITH”, filed Aug. 12, 2021, which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63/202,134, entitled “HANDHELD COMMUNICATION DEVICE WITH DRIVE-SENSE CIRCUIT BASED IMAGING ARRAY AND METHODS FOR USE THEREWITH”, filed May 28, 2021, both 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 digital imaging systems used in communication devices and more particularly to sensed data collection from imaging sensors. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG.  1    is a schematic block diagram illustrating an example of an imaging device; 
         FIG.  2    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s); 
         FIG.  3    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s); 
         FIG.  4    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s); 
         FIG.  5    is a schematic block diagram illustrating an example of a pixel sensor; 
         FIG.  6    is a schematic block diagram illustrating an example of a drive-sense circuit; 
         FIG.  7 A  is a schematic diagram illustrating an example of a pixel sensor; 
         FIG.  7 B  is a schematic diagram illustrating an example of a pixel sensor; 
         FIG.  8    is a graphical diagram illustrating an example of diode voltages; 
         FIG.  9    is a schematic block diagram illustrating an example of a drive-sense circuit; 
         FIG.  10    is a flow diagram illustrating an example method; 
         FIGS.  11  and  12    are schematic diagrams illustrating examples of a pixel sensor; 
         FIG.  13    is a schematic block diagram illustrating an example of an analog reference generator; 
         FIG.  14    is a schematic block diagram illustrating an example of a look-up table; 
         FIG.  15    is a schematic diagram illustrating an example of a pixel sensor; 
         FIG.  16    is a flow diagram illustrating an example method; 
         FIGS.  17 A and  17 B  are schematic diagrams illustrating examples of a pixel sensor; 
         FIG.  18    is a flow diagram illustrating an example method; 
         FIG.  19    is a schematic block diagram illustrating an example of an analog reference generator; 
         FIG.  20 A  is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s); 
         FIG.  20 B  is a graphical diagram illustrating an example diode voltage; 
         FIG.  21    is a flow diagram illustrating an example method; 
         FIG.  22    is a timing diagram illustrating an example shutter control; 
         FIG.  23    is a schematic block diagram illustrating an example of an analog reference generator; 
         FIG.  24 A  is a schematic block diagram illustrating an example of a drive-sense circuit; 
         FIG.  24 B  is a schematic block diagram illustrating an example of a drive-sense circuit; 
         FIG.  25 A  is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s); 
         FIG.  25 B  is a schematic block diagram illustrating an example of an analog reference generator; 
         FIG.  26    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s); 
         FIG.  27    is a flow diagram illustrating an example method; 
         FIG.  28    is a schematic block diagram illustrating an example of a pixel array with dark pixels; 
         FIG.  29    is a schematic block diagram illustrating an example of a pixel array with dark pixels; 
         FIG.  30    is a schematic block diagram illustrating an example of a pixel array with dark pixels; 
         FIG.  31    is a flow diagram illustrating an example method; 
         FIG.  32    is a flow diagram illustrating an example method; 
         FIG.  33    is a flow diagram illustrating an example method; 
         FIG.  34    is a flow diagram illustrating an example method; 
         FIG.  35    is a flow diagram illustrating an example method; 
         FIG.  36    is a flow diagram illustrating an example method; 
         FIG.  37    is a flow diagram illustrating an example method; 
         FIG.  38    is a flow diagram illustrating an example method; 
         FIG.  39    is a schematic block diagram illustrating an example of a handheld communication device; 
         FIG.  40    is a schematic block diagram illustrating an example of an electron microscope; 
         FIG.  41    is a schematic block diagram illustrating an example of a night vision device; 
         FIG.  42    is a schematic block diagram illustrating an example of a satellite imaging device; 
         FIG.  43    is a schematic block diagram illustrating an example of an imaging device; 
         FIG.  44    is a schematic block diagram illustrating an example of an imaging device; 
         FIG.  45    is a schematic block diagram of a LIDAR device; 
         FIG.  46    is a schematic block diagram illustrating an example of an imaging device; 
         FIG.  47    is a flow diagram illustrating an example method; 
         FIG.  48    is a flow diagram illustrating an example method; 
         FIG.  49    is a flow diagram illustrating an example method; 
         FIG.  50    is a flow diagram illustrating an example method; and 
         FIG.  51    is a flow diagram illustrating an example method. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a schematic block diagram illustrating an example of an imaging device  14 . In particular, the imaging device  14  can be a digital video camera, a digital still image camera or any other electronic device that captures, processes, transmits and/or stores still images or video images based on incident light or other radiation, inside or outside of the optical spectrum. 
     The imaging device  14  includes a display device  16  such as a touch screen or other display, an imaging array with one or more drive-sense circuit(s)  20 , a core control module  40 , one or more processing modules  42 , one or more main memories  44 , cache memory  46 , a 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 and, in an alternative example, has a direction connection to the main memory  44 . In an alternate example, 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). While an architecture is presented having a particular interconnection scheme, a fewer or greater number of interconnections are likewise possible and further one or more buses may likewise be employed. 
     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 (4th 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 retrieved 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 memories ( 64 ,  66 , etc.) are 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 example, the I/O and/or peripheral control module  52  includes one or more Peripheral Component Interface (PCI) buses or other interfaces to which peripheral components connect to the core control module  40 . A memory interface module  62  can include 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  can be in accordance with a Serial Advanced Technology Attachment (SATA) port or other memory interface. 
     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 cards ( 68 ,  70 , etc.) can include wireless communication units and/or a wired communication units. Such a wireless communication unit can include a wireless local area network (WLAN) communication device that operates, for example in accordance with a 802.11 protocol or other wireless local area network protocol, a cellular data communication device, a Bluetooth device, a ZigBee communication device and/or other wireless communication interface. Such a wired communication unit can include a Gigabit LAN connection, a Firewire connection, a universal serial bus (USB) interface and/or other wired interface. The network interface module  60  includes a software driver and a hardware connector for coupling the network card(s) to the I/O and/or peripheral control module  52 . For example, the network interface module  60  can operate in accordance with one or more versions of IEEE 802.11, cellular telephone protocols, 10/100/1000 Gigabit LAN protocols, an internet protocol, 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, 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 example, 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  can include one or more speakers, headphones, earphones or other output device(s). An output interface module  58  can include a software driver and a hardware connector for coupling an output device to the I/O and/or peripheral control module  52 . In an example, an output interface module  56  is in accordance with one or more audio codec protocols. 
     The imaging array with drive-sense circuit(s)  20  includes an imaging array with a plurality of pixel sensors coupled to one or more plurality of drive-sense circuits (DSC). In general, the pixel sensors (e.g., CMOS pixel sensors or other pixel sensors) detect incident light in the form of photons and/or other radiation in a non-optical spectrum. For example, when light or other radiation from a scene to be captured enters the imaging array with drive-sense circuit(s)  20 , one or more electrical characteristics of the pixel sensors change as a result. One or more drive-sense circuits (DSC) coupled to the affected pixel sensors detect these changes and generates sensed signals representative of these changes to the graphics processing module  48 , which may be a separate processing module or integrated into one or the processing module(s)  42 . 
     In various examples, the graphics processing module  48  includes at least one control signal generator  96  that operates to generate column and row selection signals for addressing/selecting the individual pixel sensors of the imaging array to be sensed by one or the drive-sense circuit(s)  20  and further that generates one or more other control signals  90  for the imaging array with drive-sense circuit(s)  20  such as timing signals for synchronizing the detection of these changes, resetting the pixel sensors after they are sensed, and/or transfer signals for pixel circuits with transfer gates, etc. In addition, when video signals are produced by the graphics processing module  48 , the column and row selection signals ( 92 ,  94 ) and control signals  90  can support the formation of frames of video data. The at least one control signal generator  96  can further operate to generate one or more analog reference signals used in the operation of the drive-sense circuits. Further discussion of this feature including several examples will be discussed in conjunction with the Figures that follow, particularly in conjunction with  FIGS.  12 - 16 ,  18 - 19 ,  21 ,  23 ,  24 A -B,  27 , etc. The control signal generator  96  can include, for example: one or more oscillators, clock signal generators and/or other timing generation circuits; a row driver, column driver and/or other pixel addressing circuits; one or more analog reference signal generators; and/or other processing circuits for generating the various control signal inputs to the imaging array with drive-sense circuit(s)  20  discussed herein. 
     The graphics processing module  48  further includes at least one preprocessing module  98  such as one or more buffers, a frame grabber and/or other processing circuitry that processes sensed signals from the drive-sense circuits into pixel data such as digital representations of intensity and/or color, that in conjunction with the corresponding addresses of the pixel sensors and/or timing, can be used by the graphics processing module  48  to generate frames of still image data and/or video data to be displayed by the display device  16 , output to the core control module  40  for storage in a memory  64  or  66 , and/or for transmission via network card  68 ,  70 , etc. While the preprocessing module  98  and control signal generator  52  are shown as being a part of the graphics processing module  48 , either device or both devices could instead be implemented as a part of the imaging array with drive-sense circuit(s)  20  or as part of a separate processing module or modules  42 . 
     Furthermore, the processing module  42  can communicate directly with a graphics processing module  48  to display other data on the display  16 . The display  16  can 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  can receive 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  16 . 
     Further functions, features, implementations and applications of the imaging array with drive-sense circuit(s)  20  will be discussed in conjunction with the Figures that follow. These functions, features, implementations and applications of the imaging array with drive-sense circuit(s)  20  can be used in combination or as alternatives. It should be noted that, in various embodiments, the use of one or more drive sense circuits allows the complexity of pixel sensors to be reduced, increasing pixel fill factor and decreasing power consumption, temperature and resulting dark current. Furthermore, the drive sense circuit(s) can promote the cancellation of spatial noise, dark current and other undesirable quantities via the use of an analog reference signal generated based on double sampling, reference pixels, and/or dark pixels, etc. 
       FIG.  2    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s). In particular, an imaging array with drive-sense circuit  20 - 1  is shown in conjunction with graphics processing module  48 . In the example shown, the imaging array with drive-sense circuit(s)  20 - 1  includes a plurality of pixel sensors (PS)  85  that are supported via a single drive-sense circuit  28 . 
     In various examples, the pixel sensors  85  are individually addressable by row select  80  and column select  82  in response to row address signal  92  and column address signal  94  generated by the graphics processing module  48 . Once an individual pixel sensor  85  is addressed, it is coupled to the drive-sense circuit  28  and a sensed signal  120  is generated that indicates, for example, the intensity of the incident light on the pixel sensor. After all of the individual pixel sensors  85  are addressed, the corresponding set of sensed signals  120  can be used to generate an entire image or frame of data. This process can be repeated to generate additional images and/or successive frames of video at a frame rate that set by the graphics processing module  48 . Furthermore, the graphics processing module may be configured to address only a proper subset of the pixel sensors to generate an image or frame with less than the full resolution of the full array and/or to generate only a portion of the full image or frame that is possible. 
     In various examples, the pixel sensors  85  each include a low-power circuit such as a photo diode and CMOS circuit that operate under the control of one or more control signals  90  generated by the graphics processing module  48 . For example, each pixel sensor  85  can be implemented as a passive pixel sensor, an active pixel sensors (APS) such as a 3T-APS pixel sensor, 4T-APS pixel or other active designs with amplification and/or other pixel designs without amplification that are at least partially driven by the drive-sense circuit  28  and merely include CMOS circuits as switches to control the selection, transfer of charge or voltage and/or reset of the photodiode or other light sensitive element after a sensed signal  120  has been generated. Furthermore, the pixel sensors  85  can be implemented via a CCD pixel sensor and/or other pixel sensor designs. 
     In operation, the pixel sensors  85  detect incident light in the form of photons and/or other radiation in a non-optical spectrum. When light or other radiation from a scene to be captured enters the imaging array with drive-sense circuit(s)  20 , one or more electrical characteristics of the pixel sensors  85  change as a result. The drive-sense circuit  28  detects these changes and generates sensed signals  120  representative of these changes for processing by the preprocessing module  98 . 
     The pixel sensors  85  are oriented in an accordance with the X-Y coordinate system as shown, where rows are parallel with the X axis and columns are parallel with the Y axis. It should be noted however, that other orientations are possible with rows and columns reversed. More generally, the “rows” correspond to a first direction or trajectory and “columns” correspond to a second direction or trajectory that differs from the first direction or trajectory. Furthermore, while these two directions are shown as being perpendicular, other non-perpendicular implementations are likewise possible. 
     In an example of operation, the drive-sense circuit  28  generates the sensed signal  120  corresponding to one of the plurality of pixel sensors  85 , via a first conversion circuit configured to convert a receive signal component of a sensor signal  116  corresponding to the one of the plurality of pixel sensors into the sensed signal  120 . In particular, the sensed signal  120  indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors  85 . A second conversion circuit of the drive-sense circuit  28  is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  corresponding to the one of the plurality of pixel sensors. This process can be repeated for other pixel sensors  85  coupling the drive-sense circuit  28 , one-by-one, to individual ones of the other pixel sensors  85 , to generate a plurality of other sensed signals  120  corresponding to other ones of the plurality of pixel sensors  85 . Image data can then be generated by the graphics processing module  48 , based on the sensed signal  120  and the plurality of other sensed signals  120 . 
     As previously discussed, the sensed signal  120  is generated that indicates the intensity of the incident light (or other radiation on the pixel sensor. This can be accomplished by generating the sensed signal  120  to indicate a change in one or more electrical characteristics of the pixel sensor  85  that by themselves or collectively indicate the intensity of the incident light. The electrical characteristic(s) can include a voltage, current, charge, capacitance, reactance, impedance, or other electrical characteristic of the pixel sensor  85 . 
     In various examples, the first conversion circuit is configured to convert, based on an analog reference signal, the receive signal component of the sensor signal  116  corresponding to the one of the plurality of pixel sensors into the sensed signal  120 . The analog reference signal can be generated based on nominal reference data that indicates a selected electrical characteristic (such as a voltage, current, charge, capacitance, reactance, impedance, or other electrical characteristic) of the one of the plurality of pixel sensors  85  in an absence of the incident light. Furthermore, the nominal reference data used by the first conversion circuit to generate the sensed signal  120  can also be used by the first conversion circuit to generate the plurality of other sensed signals  120  corresponding to the other ones of the plurality of pixel sensors  85 . Alternatively, the nominal reference data can be customized to the one of the plurality of pixel sensors  85 , and the first conversion circuit can generate the plurality of other sensed signals  120  corresponding to the other ones of the plurality of pixel sensors  85 , based on a plurality of other nominal reference data customized to the other ones of the plurality of pixel sensors  85 . In this fashion, the sensed signal  120  for each pixel sensor  85  can be generated based on nominal reference data that is selected for that each pixel sensor  85 . 
       FIG.  3    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s). In particular, an imaging array with drive-sense circuits  20 - 2  is shown in conjunction with graphics processing module  48 . Similar elements from  FIG.  2    are referred to by common reference numerals. In the example shown, the imaging array with drive-sense circuits  20 - 2  includes a plurality of pixel sensors  85  that are supported via an entire row of drive-sense circuits  28 . 
     In operation, row select  80  operates to couple an entire rows of pixels sensors  85  to the drive-sense circuits  28  which generate a corresponding plurality of sensed signals  120 , one for each of the pixel sensors  85  in the row. After all of the rows of pixel sensors  85  are selected, the corresponding set of sensed signals  120  can be used to generate an entire image or frame of data. This process can be repeated to generate additional images and/or successive frames of video at a frame rate that set by the graphics processing module  48 . Furthermore, the graphics processing module  48  may be configured to address only a proper subset of the pixel sensors to generate an image or frame with less than the full resolution of the full array and/or to generate only a portion of the full image or frame that is possible. 
     In an example of operation, each drive-sense circuit  28  generates the sensed signal  120  corresponding to one of the pixel sensors  85  in a selected row via a first conversion circuit configured to convert a receive signal component of a sensor signal  116  corresponding to the one of the plurality of pixel sensors into the sensed signal  120 . In particular, each sensed signal  120  indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors of the selected row. A second conversion circuit of the drive-sense circuit  28  is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  corresponding to the one of the plurality of pixel sensors in the selected row. This process can be repeated for other rows pixel sensors  85  by generating, via the drive-sense circuit  28 , a plurality of other sensed signals  120  corresponding to other pixel sensors  85  in other rows. Image data can then be generated by the graphics processing module  48 , based on the sensed signal  120  and the plurality of other sensed signals  120 . 
     While the description above has focused on scanning a row of drive-sense circuits  28  through various rows of pixel sensors  85 , in the alternative, a column of drive-sense circuits  28  could be provided that scans through the various columns of pixel sensors  85 . 
       FIG.  4    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s). In particular, an imaging array with drive-sense circuits  20 - 3  is shown in conjunction with graphics processing module  48 . Similar elements from  FIG.  2    are referred to by common reference numerals. In the example shown, the imaging array with drive-sense circuits  20 - 3  includes a plurality of pixel sensors (PS)  85 ′ that are each include a pixel sensor  85  and a dedicated drive-sense circuit  28  having a first conversion circuit  110  and a second conversion circuit  112  as shown in conjunction with  FIG.  5   . 
     In various examples, the pixel sensors  85 ′ are individually addressable by row select  80  and column select  82  in response to row address signal  92  and column address signal  94  generated by the graphics processing module  48 . Once an individual pixel sensor  85 ′ is addressed, its corresponding drive-sense circuit  28  generates a corresponding sensed signal  120  that indicates the intensity and/or color of the incident light on the pixel sensor. After all of the individual pixel sensors  85 ′ are addressed, the corresponding set of sensed signals  120  can be used to generate an entire image or frame of data. This process can be repeated to generate additional images and/or successive frames of video at a frame rate that set by the graphics processing module  48 . Furthermore, the graphics processing module may be configured to address only a proper subset of the pixel sensors to generate an image or frame with less than the full resolution of the full array and/or to generate only a portion of the full image or frame that is possible. 
     In an example of operation, each drive-sense circuit  28  generates the sensed signal  120  corresponding to one of the pixel sensors  85 , via a first conversion circuit  110  configured to convert a receive signal component of a sensor signal  116  corresponding to the one of the plurality of pixel sensors into the sensed signal  120 . In particular, each sensed signal  120  indicates a change in an electrical characteristic associated with the corresponding one of the plurality of pixel sensors  85 . The second conversion circuit  112  of the drive-sense circuit  28  is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  corresponding to the corresponding one of the plurality of pixel sensors  85 . Image data can then be generated by the graphics processing module  48 , based on the sensed signals  120  for all of the array. 
       FIG.  6    is a schematic block diagram illustrating an example of a drive-sense circuit. In particular a drive-sense circuit  28  is shown that includes a first conversion circuit  110  and a second conversion circuit  112 . As previously discussed, the drive-sense circuit  28  generates the sensed signal  120  corresponding to one of the pixel sensors  85 , via a first conversion circuit  110  configured to convert a receive signal component of the sensor signal  116  of the pixel sensor  85  into the sensed signal  120 . A second conversion circuit  112  of the drive-sense circuit  28  is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  corresponding to the corresponding one of the plurality of pixel sensors  85 . 
     The first conversion circuit  110  functions to generate the sensed signal  120  to correspond to changes in a receive signal component  118  of the sensor signal  116 . For example, the sensed signal  120  indicates a change in an electrical characteristic associated with the pixel sensor  85 . The second conversion circuit  112  functions to generate a drive signal component  114  of the sensor signal based on the sensed signal  120  to substantially compensate for changes in the receive signal component  118  such that, for example, the sensor signal  116  remains substantially constant. 
     In various examples, the drive signal component  114  of the sensor signal  116  can be a voltage or current. The sensed signal  120  can indicate a change in an electrical characteristic associated with the pixel sensor  85 , such as a voltage, current, charge, capacitance, reactance, impedance, or other electrical characteristic of the pixel sensor  85 . 
       FIG.  7 A  is a schematic diagram illustrating an example of a pixel sensor. In this example, a passive pixel sensor  85 - 0  is shown that includes a CMOS switch, responsive to row signal  92 . The sensor signal  116  is coupled to the drive-sense circuit  28 , that generates a sensed signal  120  in response. 
     In an example of operation, the photodiode is left floating for a certain amount of time, (an integration time), where an electric charge is generated across the photodiode in response to incident light. At the end of the integration time, the control signal  90 - 1  closes the CMOS switch and the charge is then carried off the pixel sensor as sensor signal  116 . The sensor signal  116  has a drive signal component  114  generated by the drive-sense circuit  28 . A receive signal component of the sensor signal  116  is used to generate a sensed signal  120 . 
     This particular configuration requires just one transistor which makes the pixel sensor design small and easy to implement. The photodiode can take up more space in relation to the drive-sense circuit  28 —particularly in circumstances where only a single drive-sense circuit  28  or single drive-sense circuit  28  is employed. Therefore, the fill factor of pixel sensor  85 - 0  can be larger than the fill factor of other designs with a higher quantum efficiency compared to, for example, active pixel sensors requiring more space for additional CMOS circuitry. In operation, the drive-sense circuit  28  detects changes in one or more electrical characteristics of the pixel sensor  85 - 0 , caused by changes in the charge transferred via sensor signal  116 . 
       FIG.  7 B  is a schematic diagram illustrating an example of a pixel sensor. In this example, a more abstract representation designated pixel sensor  85 - 1  is shown that includes a switch, responsive to control signal  90 - 1  that can be implemented via a single CMOS transistor. 
     In an example of operation is shown graphically in  FIG.  8   . At some initial time t 0 , the reset switch is closed, the photodiode is reverse biased and the diode voltage, V D , is pinned to the reset voltage. At time t 1 , the reset switch is opened and the diode voltage begins to drop. In particular, the drop in the diode voltage V D  beginning at time t 1  can be expressed by the following relationship: 
     
       
      
       dV 
       D 
       /dt=−I/C 
       PD  
      
     
     where I represents the photodiode current and C PD  represents the capacitance of the photodiode. The photodiode current has two primary components, a dark current I D , generated by internal factors of the photodiode itself and a photo current I PH  that is proportional to the incident light on the photodiode. The dark current, for example, can be caused by diffusion, generation recombination currents, tunneling currents, surface leakage current, Frankel-Poole currents, impact ionization current and/or other factors and be dependent upon device temperature. Considering the nominal case (in the absence of incident light), 
     
       
      
       I 
       (nominal) 
       =I 
       D  
      
     
       And 
     
       
      
       dV 
       D(nominal) 
       /dt=−I 
       (nominal) 
       /C 
       PD  
      
     
     In this case, the diode voltage V D  falls relatively slowly as shown in  FIG.  8   . In the presence of light, 
     
       
      
       I 
       (photo) 
       =I 
       D 
       +I 
       PH  
      
     
       And 
     
       
      
       dV 
       D(photo1) 
       /dt=−I 
       (photo) 
       /C 
       PD  
      
     
     In this case, the diode voltage V d  falls more rapidly due to the increased current as shown in  FIG.  8   . Furthermore, the increase in negative slope is proportional to the intensity (amount) of incident light on the surface of the photodiode. This change is slope after t 1  and/or the difference in diode voltage V D  between V D(nominal)  and V D(photo)  are examples of electrical characteristics that can be sensed by drive-sense circuit  28  as sensed signal  120 . 
       FIG.  9    is a schematic block diagram illustrating an example of a drive-sense circuit. The first conversion circuit  110  includes a comparator (comp) and an analog to digital converter (ADC)  130 . The second conversion circuit  112  includes a digital to analog converter (DAC)  132 , a signal source circuit  133 , and a driver. 
     In an example of operation, the comparator compares the sensor signal  116  to an analog reference signal  122  to produce an analog comparison signal  124 . The inclusion of this analog reference signal  122  allows, for example, the drive-sense circuit  28  to compensate for dark current, fixed biases and/or other nominal operating conditions and characteristics that are either common to all of the pixel sensors  85  or customized of each of the individual pixel sensors  85 . In particular, analog reference signal  122  can be generated based on nominal analog reference data, such as nominal measurements of sensed signal  120  for a single pixel sensor, a group of pixel sensors, a reference pixel, a group of reference pixels, etc. Such measurements can be generated, for example, based on a sampled value of V D(nominal) , values of V D(nominal)  over time, a slope of V D(nominal) , and/or other electrical characteristics of a pixel sensor  85 , such as a charge, current, capacitance, reactance, impedance, etc. 
     The analog to digital converter  130  converts the analog comparison signal  124  into the sensed signal  120 . The analog to digital converter (ADC)  130  may be implemented in a variety of ways. For example, the (ADC)  130  can include: 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 digital to analog converter (DAC)  132  converts the sensed signal  120  into an analog feedback signal  126 . The signal source circuit  133  (e.g., a dependent current source, a linear regulator, a DC-DC power supply, etc.) generates a regulated source signal  135  (e.g., a regulated current signal or a regulated voltage signal) based on the analog feedback signal  126 . The driver increases power of the regulated source signal  135  to produce the drive signal component  114 . 
       FIG.  10    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 9   . In step  170  an analog reference signal is generated. As previously discussed, an analog reference signal, such as analog reference signal  122  can be generated based on nominal analog reference data, such as nominal measurements of sensed signal  120  for a single pixel sensor, a group of pixel sensors, a reference pixel, a group of reference pixels, etc. Such measurements can be generated, for example, based on a sampled value of V D(nominal) , values of V D(nominal)  over time, a slope of V D(nominal) , and/or other electrical characteristics of one or more pixel sensor  85 , such as a charge, current, capacitance, reactance, impedance, etc. 
     In step  172 , the sensed signal is generated, via a drive-sense circuit  120  for example, based on a difference from the analog reference signal that was generated. In step  174 , the sensed signal is converted to pixel intensity/color. In step  176 , image/frame data is generated by repeating this process for some or all of the pixels in the array. 
       FIG.  11    is a schematic diagram illustrating an example of a pixel sensor. In particular, a pixel sensor  85 - 2  is shown that is implemented via a 3T APS circuit having a photodiode and three CMOS transistors. The photodiode lies in the photo-sensitive region of the pixel sensor  85 . 
     In operation, the photodiode collects charge proportional to the number of photons hitting its surface. Each row of pixels is connected to a select transistor that determines which row of pixels has been selected for read out at any one time. Once a row select transistor has been engaged via row signal  92 , the pixel is reset by disabling the reset transistor (which acts as a switch) via control signal  90 - 1  and the charge accumulated by the photodiode during a light detection, or integration, period is buffered by a source follower transistor before being transferred to a column bus connecting each pixel in a single column. This voltage can be held by a sample-and-hold capacitor of the column bus until it is time for that column bus to be read out or the sample-and-hold capacitor can be omitted with the voltage of sensor signal  116  being directly converted to the sensor signal  120  via the drive-sense circuit  28 . 
     Because the 3T pixel is an active pixel sensor (APS), there is an amplifier in each pixel in form of a source follower, which means the total area of the pixel that is photo-sensitive is reduced. This lowers the pixel&#39;s fill factor (the percentage of the pixel occupied by the photodiode and any other unused space) compared to a simpler form of passive pixel sensor. An additional problem is that each amplifier will be slightly different, resulting in spatial offsets, such as fixed pattern noise, throughout the sensor. Fixed pattern noise is more pronounced vertically if additional amplifiers are present in the column circuitry. 
     While the use of appropriate analog reference signals  122  by the drive-sense circuit can help compensate for this noise, given the drive-sense functionality of the drive-sense circuit  28 , the source follower transistor is largely redundant and can be omitted, yielding a passive design with only two transistors that operate as reset and row select switches as shown as pixel sensor  85 - 3  of  FIG.  12   . This not only increases the pixel&#39;s fill factor, it also helps to reduce the fixed pattern noise of the pixel sensor. 
       FIG.  13    is a schematic block diagram illustrating an example of an analog reference generator. In the example shown, an analog reference generator  164  generates the analog reference signal  122  in response to nominal analog reference data  160 . The analog reference signal generator  164  can be included in the drive-sense circuit  28  or provided as a separate device. 
     The nominal analog reference data  164  can represent nominal measurements of sensed signal  120  and/or other nominal electrical characteristics for a single pixel sensor, a group of pixel sensors, a reference pixel, a group of reference pixels, etc. Such measurements can be generated, for example, based on a sampled value of V D(nominal) , values of V D(nominal)  over time, a slope of V D(nominal) , measured values of sensed signal  120  under nominal conditions (in the absence of light) and/or other electrical characteristics of one or more pixel sensor  85 , such as a charge, current, capacitance, reactance, impedance, etc. In various examples, the analog reference generator  164  can include a sigma-delta DAC, a pulse width modulator DAC, a binary weighted DAC, a successive approximation DAC, and/or a thermometer-coded DAC or other circuit that converts digital to analog signals. 
     Consider the case where a common set of nominal analog reference data  160  is used for all or a group of pixel sensors  85 . Nominal measurements taken for a reference pixel can be stored as nominal analog reference data  160  and used as a representation of the nominal conditions of these pixel sensors. Furthermore, nominal measurements taken for a group of reference pixels or all or a group of the pixel sensors  85  can be averaged and stored as nominal analog reference data  160  and used as an average representation of the nominal conditions of these pixel sensors. In the alternative, nominal measurements taken for each pixel sensor  85  can be stored as nominal analog reference data  160  and used as a representation of the nominal conditions of each of these corresponding pixel sensors. 
       FIG.  14    is a schematic block diagram illustrating an example of a look-up table. In particular, look up-table  168  provides nominal analog reference data  166  that is customized for individual pixel sensors  85 . The look up-table  168  can be included in the drive-sense circuit  28  or provided as a separate device. 
     In operation, nominal measurements taken for each pixel sensor  85  can be stored as nominal analog reference data  160  in the look-up table and indexed, for example by the X-Y coordinates identifying pixel row/column or other identifying information of each pixel. When a pixel sensor selection signal indicates the identifying information of the pixel sensor in conjunction, for example, with an upcoming sensing of that pixel sensor by a drive-sense circuit  28 , the nominal analog reference data  160  for that particular pixel sensor  85  can be retrieved for use by the analog reference generator  164  in generating an analog reference signal  122  that is customized to that particular pixel. 
       FIG.  15    is a schematic diagram illustrating an example of a pixel sensor. In particular, a pixel sensor  85 - 4  similar to pixel sensor  85 - 3  is shown. While a row selection transistor has been omitted, it can be included, particularly in circumstances where the pixel sensor is implemented as part of imaging array with drive-sense circuit  20 - 1  or imaging array with drive-sense circuits  20 - 2  presented in conjunction with  FIGS.  2  and  3   . 
     In this case the sensed signal  116  is based on V D  and consider again the relationship between V D  and I where 
     
       
      
       dV 
       D 
       /dt=−I 
       D 
       /C 
       PD  
      
     
     In the presence of light, the current I changes this differential equation from 
         dV   D   /dt =−( I   D   +I   PH )/ C   PD  
 
     While, as previously discussed, the detection of changes in the voltage V D  by a drive-sense circuit  28  can be used to indicate an amount of incident light on a pixel sensor, this also indicates that the detection of changes in current I by a drive-sense circuit can also be used for this purpose. 
     Furthermore, this change in current in the presence of incident light can also be characterized as a change in capacitance from C PD  to a new effective capacitance, C eff  of the pixel sensor  85 - 4  based on nominal dark current I D  or 
     
       
      
       dV 
       D 
       /dt=−I 
       D 
       /C 
       eff  
      
     
     In this case, 
       − I   D   /C   eff =−( I   D   +I   PH )/ C   PD  
 
     Solving for this new effective capacitance, C eff  yields 
         C   eff   =C   PD ( I   D /( I   D   +I   PH )) 
     Because I D  and I PH  are both positive quantities, this means that the presence of incident light lowers the effective capacitance of the pixel sensor  85  from C PD  to C eff . This effect can be seen clearly when referring back to  FIG.  8    since the voltage drops more quickly when light is present. Therefore the effect of incident light on the pixel sensor  85  can be measured by the drive-sense circuit  28  a change in the effective capacitance from C PD  to C eff  as measured from the sensor signal  116  by the drive-sense circuit  28  when generating the sensed signal  120 . Furthermore, detecting changes in reactance and/or impedance caused by the change in capacitance can likewise be effective. 
     In addition, when the sensed signal  120 , for example, indicates the effective capacitance C eff , this quantity can then be preprocessed to generate the intensity of the incident light because this intensity is proportional to I PH . In particular, the nominal values of C PD  and I D  can be determined either on a common or customized basis from nominal analog reference data and/or V D(nominal) , values of V D(nominal)  over time, a slope of V D(nominal) , etc. In this case, 
         I   PH   =I   D ( C   PD   −C   eff )/ C   eff    
     Therefore, sensing changes in capacitance (and likewise, corresponding changes in reactance and/or impedance) can be used to indicate an amount/intensity of incident light. When pixel sensors  85  are implemented with different color filters to generate color images, the color information corresponding to each pixel sensor can be used to generate an amount/intensity of incident light of that corresponding color. 
     In an example of operation, the drive-sense circuit  28  generates a sensed signal  120  via a first conversion circuit configured to convert, a receive signal component of a sensor signal  116  of the pixel sensors  85  into the sensed signal  120 , wherein the sensed signal  120  indicates a change in a capacitance associated with the pixel sensors  85 . A second conversion circuit is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  of the pixel sensors. 
     In a further example of operation, the drive-sense circuit  28  generates a sensed signal  120  via a first conversion circuit configured to convert, a receive signal component of a sensor signal  116  of the pixel sensors  85  into the sensed signal  120 , wherein the sensed signal  120  indicates a change in a reactance associated with the pixel sensors  85 . A second conversion circuit is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  of the pixel sensors. 
     In another example of operation, the drive-sense circuit  28  generates a sensed signal  120  via a first conversion circuit configured to convert, a receive signal component of a sensor signal  116  of the pixel sensors  85  into the sensed signal  120 , wherein the sensed signal  120  indicates a change in an impedance associated with the pixel sensors  85 . A second conversion circuit is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  of the pixel sensors. 
     In an additional example of operation, the drive-sense circuit  28  generates a sensed signal  120  via a first conversion circuit configured to convert, a receive signal component of a sensor signal  116  of the pixel sensors  85  into the sensed signal  120 , wherein the sensed signal  120  indicates a change in a current associated with the pixel sensors  85 . A second conversion circuit is configured to generate, based on the sensed signal  120 , a drive signal component of the sensor signal  116  of the pixel sensors. 
       FIG.  16    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 15   . 
     In step  150  an analog reference signal is generated. For example, an analog reference signal, such as analog reference signal  122  can be generated based on nominal analog reference data that indicates a nominal capacitance C PD . In step  152 , the sensed signal is generated, via a drive-sense circuit  120  for example, based on a change in effective capacitance of a pixel sensor. In step  154 , the sensed signal is converted to pixel intensity/color. In step  156 , image/frame data is generated by repeating this process for some or all of the pixels in the array. 
       FIG.  17 A  is a schematic diagram illustrating an example of a pixel sensor. In particular, a pixel sensor  85 - 5  is shown that is implemented via a 4T APS circuit having a photodiode and four CMOS transistors—including a CMOS switch operating as a transfer gate in response to control signal  90 - 2 . 
     In this example, a pinned photodiode is used with an extra thin p-type implant at its surface. When a voltage (called the pinning voltage) is applied to the diode, two depletion regions form near the back-to-back diodes. When these two regions meet, the diode is emptied of charge. Since there are no electrons remaining on the diode, the transfer is noiseless. 
     In operation, an integration period is completed, followed by the resetting of the separate readout node (known as a floating diffusion node). This reset value is then sampled before the transfer gate is opened in order to sample the signal value and empty the diode. This is known as correlated double sampling (CDS) and largely eliminates both fixed pattern noise and dark current noise because the noise from the floating diffusion node capacitance is read in both the signal and reset value, and thus are eliminated if the two signals are subtracted. 
     In various examples, the first conversion circuit  110  of the drive-sense circuit  28  is configured to convert a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal  120 —based on an analog reference signal. In an example of operation, the analog reference signal is generated based on the sensed signal  120  generated by the drive-sense circuit  28 , prior to enabling the transfer gate. The transfer gate is then enabled and the drive-sense circuit  28  generates a second sensed signal  120 . The use of the first sample of the sensed signal (prior to opening the transfer gate) to generate such an analog reference serves to compensate for these undesirable artifacts in the second sensed signal  120 . 
     Again, given the drive-sense functionality of the drive-sense circuit  28 , the source follower transistor is largely redundant and can be omitted, yielding a passive design with only two transistors that operate as reset and row select switches as shown as pixel sensor  85 - 6  of  FIG.  17 B . This not only increases the pixel&#39;s fill factor, it also helps to reduce the fixed pattern noise. 
       FIG.  18    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 17   . 
     In step  180  an analog reference signal is generated, via a drive-sense circuit  120  for example, based on a sensed signal before the transfer gate is enabled (opened). In step  182 , the sensed signal is generated again once the transfer gate is opened, via a drive-sense circuit  120  for example, based on a difference from the analog reference signal. In step  184 , the sensed signal is converted to pixel intensity/color. In step  186 , image/frame data is generated by repeating this process for some or all of the pixels in the array. 
       FIG.  19    is a schematic block diagram illustrating an example of an analog reference generator. In the example shown, an analog reference generator  164 ′ generates the analog reference signal  122  in response to the sensed signal  120  (a first sensed signal, e.g. before transfer) from a pixel sensor, such as pixel sensor  85 - 5  or  85 - 6  having a transfer gate or other pixel sensor that operates via coordinated double sampling. The analog reference signal generator  164 ′ can be included in the drive-sense circuit  28  or provided as a separate device. 
     The analog reference generator  164 ′ includes a buffer for temporarily storing the first sample, prior to generation of the analog reference signal  122  for generation of the second sensed signal  120 . In various examples, the analog reference generator  164 ′ can further include a sigma-delta DAC, a pulse width modulator DAC, a binary weighted DAC, a successive approximation DAC, and/or a thermometer-coded DAC or other circuit that converts digital to analog signals. 
       FIG.  20 A  is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s). In particular, an imaging array with drive-sense circuit(s)  20 - 4 , shown in schematic cross section, includes a shutter  202 , a lens  204  a color filter array  206  and a pixel array with drive-sense circuits  208 . The pixel array with drive-sense circuit(s) can be implemented via the imaging array with drive-sense circuit(s)  20 - 1 ,  20 - 2  or  20 - 3  as previously discussed. The shutter, when enabled via shutter control  90 - 3  (e.g. open), passes the incident light through the lens  204  and color filter array  206  to the pixel array with drive-sense circuit(s)  208  and when not enabled via shutter control  90 - 3  (disabled, e.g. shut), blocks the incident light. 
     The lens  204  can be implemented via a monolithic resin lens, an array of micro-lenses or other lens that directs the incident light through the color filter array to the pixels of the pixel array with drive-sense circuit(s)  208 . The color filter array  206  provides color filter separation to direct light of different colors to differing pixel sensors. In various examples, the color filter array  206  and pixel array with drive-sense circuit(s)  208  are configured in a Bayer pattern where four adjacent pixels have two green (G) pixels, one red (R) pixel and one blue (B) pixel, however, other color patterns with other colors such as emerald (E), cyan (C), yellow (Y), White (W), in patterns such as RGBE, RYYB, CYYM, CYGM, RGBW, X-Trans, RCCC, RCCB, etc. can likewise be implemented. 
     The shutter  202  can be implemented via an electromechanical shutter or electronic shutter such as a focal-plane shutter, leaf shutter, rotating shutter, diaphragm shutter, LCD shutter, rolling shutter or other shutter or shutter equivalent. The shutter  202  can be used in different ways. Referring back to  FIG.  8   , the shutter control can be synchronized with the reset control signal  90 - 1  and closed except during the times t, where 
     
       
      
       t 
       1 
       &lt;t&lt;t 
       2  
      
     
     In this fashion, the generation of I PH  is coordinated with the sensing/integration period between t 1 &lt;t&lt;t 2  or a sampling time t 2  used by the drive-sense circuit  28 —depending on the implementation. 
     In another example, the shutter  202  can be used to support another form of double sampling. In particular, nominal analog reference data  160  for some or all of the pixel sensors  85  or  85 ′ can be generated based on first sensed signals  120  when the shutter  202  is not enabled (shut). These nominal analog reference data  160  can be used to generate analog reference signal for the drive-sense circuit(s)  28  when generating second sensed signals  120  when the shutter  202  is enabled (open). 
       FIG.  20 B  is a graphical diagram illustrating an example diode voltage. In particular, a diode voltage V D  is shown as a function of time corresponding to a pixel sensor  85 . At some initial time t 0 , the reset switch and shutter  202  are both closed, the photodiode is reverse biased and the diode voltage, V D , is pinned to the reset voltage. At time t 1 , the reset switch is opened while the shutter  202  remains closed. The diode voltage begins to drop but the shutter is or remains closed. In particular, the drop in the diode voltage V D(nominal)  beginning at time t 1  can be expressed by the following relationship: 
     
       
      
       dV 
       D 
       /dt=−I 
       D 
       /C 
       PD  
      
     
     where I represents the photodiode current and C PD  represents the capacitance of the photodiode. A first sensed signal  120  generated during this period can be used to generate the nominal analog reference data for the pixel sensor, and in particular gives and indication of the actual dark current and/or nominal photodiode capacitance of this particular pixel sensor (in the absence of incident light). 
     At time t 2 , the reset switch is closed and the diode voltage is again pinned to the reset voltage which is achieved at t 3 , at which point the reset switch and shutter are both opened. In this case, the diode voltage V D  falls more rapidly in the presence of incident light, due to the increased current, increase in negative voltage slope and decreased effective capacitance. These can be sensed by drive-sense circuit  28  that uses the nominal analog reference data to generate a corresponding nominal analog reference signal. This helps compensates for the dark current of this particular pixel sensor  85  in generating the second sensed signal  120 . 
       FIG.  21    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 20   . Step  210  includes generating an analog reference signal based on a sensed signal generated by the drive-sense circuit with the shutter closed. Step  212  includes resetting the pixel sensor and generating, via the drive-sense circuit, another sensed signal based on the analog reference signal when the shutter is open. In step  214 , the sensed signal is converted to pixel intensity/color. In step  216 , image/frame data is generated by repeating this process for some or all of the pixels in the array. 
       FIG.  22    is a timing diagram illustrating an example shutter control. In the example shown, shutter control  90 - 3  toggles between closed an open for the entire array. When the shutter is closed, nominal analog reference (NAR) data are generated for some or all of the pixel sensors  85  or  85 ′ based on first sensed signals  120  from the drive-sense circuit(s)  28 . When the shutter is open, second sensed signals  120  are generated by the drive-sense circuit(s)  28  for some or all of the pixel sensors  85  or  85 ′. 
     In various embodiments, the number of shutter open periods in a second of time corresponds to a video frame rate to be generated such as 1.5 FPS, 5 FPS, 10 FPS, 15 FPS, 20 FPS, 30 FPS, 60 FPS, 120 FPS, or other higher or lower rate, etc. It should be noted that, while a timing diagram shown that alternates between open and closed conditions, in other examples, NAR data can be generated less frequently, only once at device start-up or via some other pattern. 
       FIG.  23    is a schematic block diagram illustrating an example of an analog reference generator. In the example shown, an analog reference generator  164 ′ generates the analog reference signal  122  in response to the sensed signal  120  (a first sensed signal, e.g. with the shutter closed) from a pixel sensor  85  or  85 ′. The analog reference signal generator  164 ′ can be included in the drive-sense circuit  28  or provided as a separate device. 
     The analog reference generator  164 ′ includes a buffer for temporarily storing the first sample, prior to generation of the analog reference signal  122  for generation of the second sensed signal  120 . In various examples, the analog reference generator  164 ′ can further include a sigma-delta DAC, a pulse width modulator DAC, a binary weighted DAC, a successive approximation DAC, and/or a thermometer-coded DAC or other circuit that converts digital to analog signals. 
       FIGS.  24 A and  24 B  are schematic block diagrams  28 - 3  illustrating an example of a drive-sense circuit. In particular, the drive-sense circuit  28 - 3  has many similar elements the drive-sense circuit  28 - 2  of  FIG.  9    to the that are referred to by common reference numerals. 
     In the example shown, the second conversion circuit  112  can be selectively enabled and disabled. Furthermore an implementation of double sampling is presented.  FIG.  24 A  represents a time period where the shutter is closed. An analog reference signal  122  is set to zero or some other nominal DC offset. The second conversion circuit  112  is disabled and the sensed signal  120  (shutter closed) is generated as the difference between the sensor signal  116  and analog reference signal  122 —and therefore is a representation of V D(nominal)  with or without the nominal DC offset, and consequently indicative of I D  and/or C PD . 
     The sensed signal  120  (shutter closed) can be stored as nominal analog reference data that is used by analog reference generator  164 ′ to generate an analog reference signal  122  during a later time period represented  FIG.  24 B . In this case, the second conversion circuit  112  is enabled to support the generation of sensed signal  120  (with the shutter open). 
       FIG.  25 A  is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s). Similar elements to the imaging array of  FIG.  20 A  are represented by common reference numerals. In this case, however, the shutter  202  is omitted and a color filter layer with photomasks  222  is included forming a photo array with dark pixels  220 . 
     The photomasks can be constructed of a metallic patches or other opaque portions that block incident light from reaching the surface of the dark pixels. These dark pixels can operate as reference pixels and can be constructed to mimic the functionality of the remaining pixel sensors  85  or  85 ′ of the pixel array. When sensed by a drive-sense circuit  28 , the dark pixels are used to generate sensed signals  120  representative of the nominal operation in the absence of incident light. This configuration supports dark current compensation in the drive-sense circuit via analog reference signals generated via sensed signals  120  from these dark pixels. 
     In an example of operation, nominal analog reference data for some or all of the (non-dark) pixel sensors  85  or  85 ′, such as nominal analog reference data  160 , can be generated by a drive-sense circuit  28  based on sensed signals  120  generated for these dark pixels. Similarly, the drive-sense circuit  28 - 3  configuration of  FIG.  24 B  can be employed that operates based on a zero or nominal DC offset as the analog reference signal and with the second conversion circuit disabled. In other configurations, a drive-sense circuit  28 - 2  configuration of  FIG.  9    can be employed. These nominal analog reference data  160  can be used to generate analog reference signals  122  for the drive-sense circuit(s)  28  when generating second sensed signals  120  when the shutter  202  is enabled (open). 
       FIG.  25 B  is a schematic block diagram illustrating an example of an analog reference generator. In the example shown, an analog reference generator  164 ′ generates the analog reference signal  122  in response to the sensed signal  120  from the pixel sensor  85  or  85 ′ of a dark pixel. The analog reference signal generator  164 ′ can be included in the drive-sense circuit  28  or provided as a separate device. 
     The analog reference generator  164 ′ includes a buffer or other memory for storing the sensed signal  120  corresponding to the dark pixel(s) as nominal analog reference data, prior to generation of the analog reference signal  122 . In various examples, the analog reference generator  164 ′ can further include a sigma-delta DAC, a pulse width modulator DAC, a binary weighted DAC, a successive approximation DAC, and/or a thermometer-coded DAC or other circuit that converts digital to analog signals. 
     Consider the case where a common set of nominal analog reference data  160  is used for all or a group of pixel sensors  85  or  85 ′ of the pixel array with dark pixel(s). Nominal measurements, such as sensed signal  120 , taken for a dark pixel can be stored as nominal analog reference data  160  and used as a representation of the nominal conditions for each of these pixel sensors. Furthermore, nominal measurements taken for a group of dark pixels can be averaged and stored as nominal analog reference data  160  and used as a representation of the nominal conditions for all or a group of these pixel sensors. In the alternative, nominal measurements taken for a particular dark pixel can be stored as nominal analog reference data  160  and used as a representation of the nominal conditions of only a single pixel sensor  85  or  85 ′ immediately adjacent to the dark pixel or only a small group of immediately adjacent pixel sensors  85  or  85 ′. As used herein, an immediately adjacent pixel sensor means having a physical proximity such that there are no other pixel sensors physically between the dark pixel and the immediately adjacent pixels sensor. 
       FIG.  26    is a schematic block diagram illustrating an example of an imaging array with drive-sense circuit(s). In particular, a portion of a schematic cross section of an imaging array with drive-sense circuit(s) of  FIG.  25 A  is shown. Incident light is guided by the lens array  204  through corresponding color filters  230  to corresponding live pixels sensors  85  (non-dark pixels). Conversely, photomasks  232  block the incident light from reaching the pixel sensors  85 ″ (dark pixels). While shown as pixel sensors  85  and pixel sensors  85 ″ coupled to a one or more drive-sense circuit(s)  28 , pixel sensors  85 ′ could likewise be employed for either dark or non-dark pixels. 
       FIG.  27    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 26   . Step  250  includes generating an analog reference signal based on a sensed signal generated by the drive-sense circuit for a dark pixel. Step  252  includes resetting the pixel sensor and generating, via the drive-sense circuit, another sensed signal based on the analog reference signal. In step  254 , the sensed signal is converted to pixel intensity/color. In step  256 , image/frame data is generated by repeating this process for some or all of the pixels in the array. 
       FIG.  28    is a schematic block diagram illustrating an example of a pixel array with dark pixels. In particular, a pixel array with dark pixels  220 - 1  is shown having a sub-array of (live) pixels  85  or  85 ′ and a sub-array of dark pixels  85  or  85 ′. Placing columns/rows of dark pixels between rows of live pixels have the advantage to reduce spatial variations in manufacturing and/or spatial variations of pixel temperature that have an effect on dark current. Presumably, sensed signals  120  for adjacent dark pixels, alone or averaged based on multiple adjacent dark pixels, provide the most accurate prediction/approximation of nominal electrical characteristics of the live pixels adjacent to them. 
       FIG.  29    is a schematic block diagram illustrating an example of a pixel array with dark pixels. In particular, a pixel array with dark pixels  220 - 2  is shown having a sub-array of (live) pixels  85  or  85 ′ and a sub-array of dark pixels  85  or  85 ′. Placing the dark pixels only along the periphery of the array increases the live-to-dark ratio and supports higher resolution for arrays of the same size. 
       FIG.  30    is a schematic block diagram illustrating an example of a pixel array with dark pixels. In particular, a group of 4 pixels in a pixel array with dark pixels  220 - 3  is shown. The group has 3 (live) pixel sensors  85  or  85 ′, each responding to a different color (e.g, red, green and blue) and a single of dark pixel  85  or  85 ′. In this configuration, nominal analog reference data for the dark pixel is used to generate analog reference signals  122  for each of the three live pixels in the group. 
       FIG.  31    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 31   . Step  700  includes providing a plurality of pixel sensors that respond to incident light. Step  702  includes coupling a drive-sense circuit to one of the plurality of pixel sensors in response to a row selection signal and a column selection signal. 
     Step  704  includes generating a sensed signal via the drive-sense circuit, wherein the drive-sense circuit includes: a first conversion circuit configured to convert a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  706  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors by performing steps  702  and  704  for the other ones of the plurality of pixel sensors. Step  708  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  32    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 31   . Step  720  includes providing a plurality of pixel sensors arranged in a first direction and a second direction that respond to incident light, wherein the first direction is different than the second direction. Step  722  includes coupling, in response to subset selection signal, a plurality of drive-sense circuits to a selected subset of the plurality of pixel sensors along the first direction. 
     Step  724  includes generating a plurality of sensed signals via the plurality of drive-sense circuits, wherein each of the plurality of drive-sense circuits includes: a first conversion circuit configured to convert a receive signal component of a sensor signal corresponding to one of the plurality of pixel sensors in the selected subset, into a corresponding one of the plurality of sensed signals; and a second conversion circuit configured to generate, based on the corresponding one of the plurality of sensed signals, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors in the selected subset. Step  726  includes generating a plurality of other sensed signals corresponding to other subsets of the plurality of pixel sensors in the first direction by performing steps  722  and  724  for the other subsets of the plurality of pixel sensors. Step  728  includes generating image data based on the plurality of sensed signals and the plurality of other sensed signals. 
       FIG.  33    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 32   . Step  740  includes providing a plurality of pixel sensors arranged in a first direction and a second direction that respond to incident light, wherein the first direction is different than the second direction. Step  742  includes providing a plurality drive-sense circuits, wherein each of the plurality of drive-sense circuits is coupled to a corresponding one of the plurality of pixel sensors. 
     Step  744  includes generating a plurality of sensed signals via the plurality of drive-sense circuits, wherein each of the plurality of drive-sense circuits includes: a first conversion circuit configured to convert a receive signal component of a sensor signal corresponding to the corresponding one of the plurality of pixel sensors into a corresponding one of the plurality of sensed signals; and a second conversion circuit configured to generate, based on the corresponding one of the plurality of sensed signals, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  746  includes generating image data based on the plurality of sensed signals. 
       FIG.  34    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 33   . Step  760  includes providing a plurality of pixel sensors that respond to incident light. Step  762  includes providing at least one drive-sense circuit. 
     Step  764  generating a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, based on an analog reference signal, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the analog reference signal is generated based on nominal reference data that indicates pixel sensor performance in absence of the incident light; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  766  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors by performing step  764  for the other ones of the plurality of pixel sensors. Step  768  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  35    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 34   . Step  780  includes providing a plurality of pixel sensors that respond to incident light. Step  782  includes providing at least one drive-sense circuit. 
     Step  784  includes generating a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in a capacitance associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  786  includes generating, via the at least one drive-sense circuit, a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors; and Step  788  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
     In various examples, the plurality of pixel sensors each include a CMOS circuit having a photodiode. The first conversion circuit can be configured to convert, based on an analog reference signal, the receive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the analog reference signal is generated based on nominal reference data that indicates an electrical characteristic of the one of the plurality of pixel sensors in an absence of the incident light. The nominal reference data used by the first conversion circuit to generate the sensed signal can also be used by the first conversion circuit to generate the plurality of other sensed signals corresponding to the other ones of the plurality of pixel sensors. The nominal reference data can be customized to the one of the plurality of pixel sensors and further the first conversion circuit can generate the plurality of other sensed signals corresponding to the other ones of the plurality of pixel sensors, based on a plurality of other nominal reference data customized to the other ones of the plurality of pixel sensors. The electrical characteristic can indicate a capacitance of the one of the plurality of pixel sensors in an absence of the incident light. 
     In various examples, the at least one drive-sense circuit includes a single drive-sense circuit that is selectively coupled to the one of the plurality of pixel sensors to generate the sensed signal and is selectively coupled to each of the other ones of the plurality of pixel sensors to generate the plurality of other sensed signals. The at least one drive-sense circuit can include a plurality of drive-sense circuits that is coupled to a selected subset of the plurality of pixel sensors along a first direction. The at least one drive-sense circuit can include a plurality of drive-sense circuits each coupled to a corresponding one of the plurality of pixel sensors. 
       FIG.  36    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 35   . Step  800  includes providing a plurality of pixel sensors that respond to incident light. Step  802  includes providing at least one drive-sense circuit. Step  804  includes generating an analog reference signal corresponding to one of the plurality of pixel sensors, prior to enabling the transfer gate. Step  806  includes enabling the transfer gate. Step  808  includes generating a sensed signal via the at least one drive-sense circuit corresponding to the one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, based on the analog reference signal, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. 
     Step  810  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors by performing steps  804 ,  806  and  808  for the other ones of the plurality of pixel sensors. Step  812  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  37    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 36   . Step  820  includes providing a plurality of pixel sensors that respond to incident light. Step  822  includes providing at least one drive-sense circuit. Step  824  includes providing a shutter that, when enabled, passes the incident light and when not enabled, blocks the incident light. Step  826  includes generating at least one analog reference signal corresponding to one of the plurality of pixel sensors, when the shutter is not enabled. 
     Step  828  includes generating a sensed signal via the at least one drive-sense circuit corresponding to the one of the plurality of pixel sensors when the shutter is enabled, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, based on the at least one analog reference signal, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  830  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors by performing step  828  for the other ones of the plurality of pixel sensors. Step  832  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  38    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 37   . Step  840  includes providing a plurality of pixel sensors that respond to incident light. Step  842  includes providing at least one drive-sense circuit. Step  844  includes providing at least one dark pixel that does not respond to the incident light. Step  846  includes generating at least one analog reference signal via the at least one dark pixel. 
     Step  848  includes generating a sensed signal corresponding to one of the plurality of pixel sensors via the at least one drive-sense circuit, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, based on the at least one analog reference signal, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  850  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors by performing step  848  for the other ones of the plurality of pixel sensors. Step  852  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  39    is a schematic block diagram illustrating an example of a handheld communication device. In particular, a handheld communication device  1014  is shown that includes one or more similar elements to imaging device  14  that are referred to by common reference numerals. In various embodiments, the handheld communication device  1014  can be implemented as a tablet, laptop computer, smartphone, smartwatch, smart display device, or other portable personal communication device. 
     The handheld communication device  1014  includes one or more imaging array with drive-sense circuit(s)  20  that facilitates the capture of frames of still and/or video data. The handheld communication device  1014  further includes a one or more wireless interfaces ( 72 ,  74 ) for sending and receiving data via wireless communications. The one or more wireless interfaces ( 72 ,  74 ) can include 802.11 transceivers, 4G or 5G transceivers, Bluetooth transceivers, Zigbee transceivers or other wireless interface devices that allow the handheld communication device  1014  to send and receive text and chat messages, email message, voice calls, engage in social media messaging, share audio, video, still images and/or other media. Furthermore, the display device  16  can provide a touch screen interface as a user interactive input/output device that allows the user to, for example, facilitate the capture of frames of still and/or video data, to store the still and/or video data, to append text, graphics, audio and/or other media to the still and/or video data, to upload or share the still and/or video data, to send messages that contain the still and/or video data, and/or to facilitate the other operations of the handheld communications device. 
     In an example of operation, the handheld communications device  14  operates to perform operations that include:
         providing a plurality of pixel sensors that respond to incident light;   providing at least one drive-sense circuit;   generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors.   generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit; and   generating image data based on the sensed signal and the plurality of other sensed signals for display via a touch screen.       

       FIG.  40    is a schematic block diagram illustrating an example of an electron microscope. In particular, an electron microscope is presented that includes an electron gun  1100 , one or more lenses  1102 , a specimen holder  1104  and an imaging device  14  that responds to incident electrons. 
     In operation, the electron gun generates an electron beam  1120 . The one or more lenses  1102  form the electron beam  1120  into a primary electron beam  1122  that is focused on a specimen to be imaged. The specimen holder  1104  holds the specimen. In various examples, the specimen holder  1104  can include a vacuum chamber that reduces the amount of air molecules surrounding the specimen that might be impacted by the primary electron beam, thereby reducing undesirable noise in the resultant image. The secondary electron beam  1124  results from transmission of the primary electron beam  1122  through the specimen (when implemented in a transmission electron microscope configuration) or reflection of the primary electron beam  1122  from the specimen (when implemented in a reflection electron microscope configuration). 
     In various examples, the imaging device  14  operates by:
         providing a plurality of pixel sensors that respond to an incident electron beam;   providing at least one drive-sense circuit;   generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors;   generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit; and   generating image data based on the sensed signal and the plurality of other sensed signals.       

       FIG.  41    is a schematic block diagram illustrating an example of a night vision device. The night vision device  1214  includes one or more lenses  1202  and an imaging device  14 ,  1244 - 1  or  1244 - 2 . In various examples, the night vision device  1214  can be implemented as a night vision camera, a night vision scope, a telescope, night vision goggles, or other low light or night vision imaging capture device. In operation, primary incident light  1220  from a scene  1204  is formed into secondary incident light  1222  focused on the surface of the imaging device  14 ,  1244 - 1  or  1244 - 2 . The primary incident light  1220  can be an incident low light signal that comes from the scene  1204  itself and/or can be reflected from a light source  1206  included in the night vision device  1214 . 
     In an example of operation, the imaging device  14 ,  1244 - 1  or  1244 - 2  operates by:
         providing a plurality of pixel sensors that respond to an incident low light signal;   providing at least one drive-sense circuit;   generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors;   generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit; and   generating image data based on the sensed signal and the plurality of other sensed signals.       

       FIG.  42    is a schematic block diagram illustrating an example of a satellite imaging device. The satellite imaging device  1234  includes one or more lenses  1202  and an imaging device  1244 - 2 . In operation, primary incident light  1220  from a scene  1204  is formed into secondary incident light  1222  focused on the surface of the imaging device  1244 - 2 . 
     In an example of operation, the imaging device  1244 - 2  operates by:
         providing a plurality of pixel sensors that respond to incident light;   providing at least one drive-sense circuit;   generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors;   generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit;   generating image data based on the sensed signal and the plurality of other sensed signals; and   transmitting the image data to a ground-based receiver via a wireless interface.       

       FIG.  43    is a schematic block diagram illustrating an example of an imaging device. In particular, an imaging device  1244 - 1  is shown that includes similar elements to imaging device  14  that are referred to by common reference numerals. In various implementations, the image data is merely generated and displayed by the display device  16 . In these examples, the image data may not be stored and the memory interface module(s)  62 , separate memories  64  and  66  may be omitted, in lieu of dedicated memories provided in conjunction with one or more other modules, as may be required. Furthermore, the image data may not be transmitted and the network interface module(s)  60 , separate network cards  68  and  68  may be omitted, if not required. 
       FIG.  44    is a schematic block diagram illustrating an example of an imaging device. In particular, an imaging device  1244 - 2  is shown that includes similar elements to imaging device  14  that are referred to by common reference numerals. In various implementations, the image data is merely generated and transmitted via network card  68  or  70 . In these examples, the image data may not be stored and the memory interface module(s)  62 , separate memories  64  and  66  may be omitted, in lieu of dedicated memories provided in conjunction with one or more other modules, as may be required. Furthermore, the image data may or may not be displayed and the I/O interface module  54  and display device  16  may be omitted, if not required. 
       FIG.  45    is a schematic block diagram of a LIDAR device. The LIDAR device  1214 , for example of an autonomous vehicle, includes a controllable mirror and an imaging device  1344 . The light source  1306  can be implemented via a semiconductor laser, other laser or other source of coherent light that is represented by generated light  1312 . 
     In operation, the generated light  1312  is reflected from the controllable mirror as reflected light  1314 . The controllable mirror  1310  controls the reflected light  1314  so as to scan the scene  1304  and generate, via reflection from the scene, primary incident light  1320 . The primary incident light  1320  is reflected back via the controllable mirror as secondary incident light  1322  that is incident to the surface of the imaging device  1344 . 
     In an example of operation, the imaging device  1344  operates by:
         providing at least one pixel sensor that responds to incident laser light;   providing at least one drive-sense circuit coupled to the at least one pixel sensor;   generating, a sensed signal via the at least one drive-sense circuit, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the at least one pixel sensor into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the at least one pixel sensor;   generating image data based on the sensed signal; and   transmitting the image data to an autonomous vehicle system of the autonomous vehicle.
 
In this fashion the autonomous vehicle system can use the image data for purposes of vehicle control, navigation and/or other purposes.
       

       FIG.  46    is a schematic block diagram illustrating an example of an imaging device. In particular, an imaging device  1344  is shown that includes similar elements to imaging device  14  that are referred to by common reference numerals. 
     In the example shown, the controllable mirror  1310  scans the scene under control of control signals  90  from the graphics processing module, the image data is merely generated and transmitted via network card  68  or  70 . In this example, the image data may not be displayed and the I/O interface module  54 , and display device  16  may be omitted, if not required. As shown, network card  68  is employed to communicate with an autonomous vehicle system, for example, to transmit the image data. In addition, the wireless interface  72  can communicate with an autonomous vehicle server, to receive updates, transmit image data, error reports, and/or other data. 
       FIG.  47    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 46   . Step  1400  includes providing a plurality of pixel sensors that respond to incident light. Step  1402  includes providing at least one drive-sense circuit. 
     Step  1404  includes generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  1406  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit. Step  1408  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
     In various examples, the plurality of pixel sensors each include a CMOS circuit having a photodiode. The first conversion circuit can be configured to convert, based on an analog reference signal, the receive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the analog reference signal is generated based on nominal reference data that indicates an electrical characteristic of the one of the plurality of pixel sensors in an absence of the incident light. The nominal reference data used by the first conversion circuit to generate the sensed signal can also be used by the first conversion circuit to generate the plurality of other sensed signals corresponding to the other ones of the plurality of pixel sensors. The nominal reference data can be customized to the one of the plurality of pixel sensors and further the first conversion circuit can generate the plurality of other sensed signals corresponding to the other ones of the plurality of pixel sensors, based on a plurality of other nominal reference data customized to the other ones of the plurality of pixel sensors. The electrical characteristic can indicate a capacitance of the one of the plurality of pixel sensors. 
     In various examples, the at least one drive-sense circuit includes a single drive-sense circuit that is selectively coupled to the one of the plurality of pixel sensors to generate the sensed signal and is selectively coupled to each of the other ones of the plurality of pixel sensors to generate the plurality of other sensed signals. The at least one drive-sense circuit can include a plurality of drive-sense circuits that is coupled to a selected subset of the plurality of pixel sensors along a first direction. The at least one drive-sense circuit can include a plurality of drive-sense circuits each coupled to a corresponding one of the plurality of pixel sensors. 
       FIG.  48    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 47   . Step  1420  includes providing a plurality of pixel sensors that respond to an incident electron beam. Step  1422  includes providing at least one drive-sense circuit. 
     Step  1424  includes generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  1426  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit. Step  1428  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  49    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 48   . Step  1440  includes providing a plurality of pixel sensors that respond to an incident low light signal. Step  1442  includes providing at least one drive-sense circuit. 
     Step  1444  includes generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. Step  1446  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit. Step  1448  includes generating image data based on the sensed signal and the plurality of other sensed signals. 
       FIG.  50    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 49   . Step  1460  includes providing a plurality of pixel sensors that respond to incident light. Step  1462  includes providing at least one drive-sense circuit. 
     Step  1464  includes generating, a sensed signal via the at least one drive-sense circuit corresponding to one of the plurality of pixel sensors, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the one of the plurality of pixel sensors into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the one of the plurality of pixel sensors. 
     Step  1466  includes generating a plurality of other sensed signals corresponding to other ones of the plurality of pixel sensors via the at least one drive-sense circuit. Step  1468  includes generating image data based on the sensed signal and the plurality of other sensed signals. Step  1470  includes transmitting the image data to a ground-based receiver via a wireless interface. 
       FIG.  51    is a flow diagram illustrating an example method. In particular, a method is presented for use with one or more functions/features described in conjunction with  FIGS.  1 - 50   . Step  1480  includes providing at least one pixel sensor that responds to incident laser light. Step  1482  includes providing at least one drive-sense circuit coupled to the at least one pixel sensor. 
     Step  1484  includes generating, a sensed signal via the at least one drive-sense circuit, wherein the at least one drive-sense circuit includes: a first conversion circuit configured to convert, a receive signal component of a sensor signal corresponding to the at least one pixel sensor into the sensed signal, wherein the sensed signal indicates a change in an electrical characteristic associated with the one of the plurality of pixel sensors; and a second conversion circuit configured to generate, based on the sensed signal, a drive signal component of the sensor signal corresponding to the at least one pixel sensor. Step  1486  includes generating image data based on the sensed signal. Step  1488  includes transmitting the image data to an autonomous vehicle system of the autonomous vehicle. 
     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 examples 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 examples 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 example 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 examples discussed herein. Further, from figure to figure, the examples 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. 
     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 examples. 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, a quantum register or other quantum memory and/or any other device that stores data in a non-transitory manner. Furthermore, the memory device may be in a form of a solid-state memory, a hard drive memory or other disk storage, cloud memory, thumb drive, server memory, computing device memory, and/or other non-transitory medium for storing data. The storage of data includes temporary storage (i.e., data is lost when power is removed from the memory element) and/or persistent storage (i.e., data is retained when power is removed from the memory element). 
     As used herein, a transitory medium shall mean one or more of: (a) a wired or wireless medium for the transportation of data as a signal from one computing device to another computing device for temporary storage or persistent storage; (b) a wired or wireless medium for the transportation of data as a signal within a computing device from one element of the computing device to another element of the computing device for temporary storage or persistent storage; (c) a wired or wireless medium for the transportation of data as a signal from one computing device to another computing device for processing the data by the other computing device; and (d) a wired or wireless medium for the transportation of data as a signal within a computing device from one element of the computing device to another element of the computing device for processing the data by the other element of the computing device. As may be used herein, a non-transitory computer readable memory is substantially equivalent to a computer readable memory. A non-transitory computer readable memory can also be referred to as a non-transitory computer readable storage medium. 
     While particular combinations of various functions and features of the one or more examples 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.