# US 2014/0193090 A1 · Apparatus and methods for reducing common-mode noise in an imaging system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0193090 A1 - Document ID: US20140193090A1 - Status: Published application - Kind: A1 - Application number: 14/204,832 - Filed: 2014-03-11 - Published: 2014-07-10 - Earliest claimed: 2011-07-13 - Assignees: Analog Devices, Inc. - Applicants: Analog Devices, Inc. - Inventors: Yoshinori Kusuda; Gary Robert Carreau; Michael C. Coln - Web page: https://patentgrep.com/patent/US20140193090A1 ## CPC - G06T 5/70: Denoising; Smoothing - H04L 25/028: {Arrangements specific to the transmitter end} - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Apparatus and methods reduce common-mode error. An integrated circuit includes a plurality of signal channels, a first proxy channel, and a subtraction block. The signal channels are configured to receive a plurality of input signals and to generate a plurality of output signals, and each of the signal channels has a substantially similar circuit topology. The first proxy channel has a substantially similar circuit topology as the plurality of signal channels, and includes an output that can vary in relation to a common-mode error of the signal channels. The subtraction block is configured to generate a plurality of modified output signals by using the output of the first proxy channel to reduce the common-mode error of the plurality of output signal channels. ## Claims ### Claim 1 An imaging system, comprising: a plurality of image processing circuit channels having a substantially similar circuit topology to one another, wherein the plurality of image processing circuit channels are configured to receive a plurality of image sensor signals and to process the plurality of image sensor signals to generate a plurality of analog output signals; a plurality of proxy circuit channels having a substantially similar circuit topology to one another and to the plurality of image processing circuit channels, wherein the plurality of proxy circuit channels are configured to generate a plurality of analog proxy output signals associated with a common-mode noise of the plurality of image processing circuit channels; a random noise reduction block configured to generate a common-mode noise reduction signal based on the plurality of analog proxy output signals; and a subtraction block configured to generate one or more output signals based on a difference between the common-mode noise reduction signal and one or more of the plurality of analog output signals. ### Claim 2 (depends on 1) The imaging system of claim 1, wherein the random noise reduction block is configured to generate the common-mode noise reduction signal based on an average of the plurality of analog proxy output signals. ### Claim 3 (depends on 1) The imaging system of claim 1, further comprising a processor comprising the random noise reduction block and the subtraction block, wherein the processor is configured to digitally generate the common-mode noise reduction signal, and wherein the processor is further configured to subtract the common-mode noise reduction signal from digital representations of each of the plurality of analog output signals. ### Claim 4 (depends on 3) The imaging system of claim 3, further comprising: a multiplexor configured to generate a multiplexed signal by multiplexing between the plurality of analog output signals and the plurality of analog proxy signals; and an analog-to-digital converter configured to generate a digital converted signal based on the multiplexed signal, wherein the processor is configured to receive the digital converted signal. ### Claim 5 (depends on 4) The imaging system of claim 4, wherein the processor is configured to receive digital representations of the plurality of analog output signals and of the plurality of analog proxy signals in a serial data stream. ### Claim 6 (depends on 4) The imaging system of claim 4, wherein the processor is further configured to average digital representations of the plurality of analog proxy signals to digitally generate the common-mode noise reduction signal. ### Claim 7 (depends on 4) The imaging system of claim 4, wherein the processor is further configured to generate one or more digital output signals based on subtracting the common-mode noise reduction signal from digital representations of the plurality of analog output signals. ### Claim 8 (depends on 4) The imaging system of claim 4, further comprising an amplifier configured to receive the multiplexed signal, and to amplify the multiplexed signal to generate an amplified signal, wherein the analog-to-digital converter comprises an input configured to receive the amplified signal. ### Claim 9 (depends on 1) The imaging system of claim 1, further comprising a reference voltage generation circuit configured to generate a reference voltage, wherein the plurality of imagine processing circuit channels are configured to process the plurality of image sensor signals based in part on the reference voltage, wherein the plurality of image processing circuit channels and the plurality of proxy circuit channels receive the reference voltage. ### Claim 10 (depends on 1) The imaging system of claim 1, wherein the plurality of image processing circuit channels comprise a plurality of single-ended inputs, wherein the plurality of proxy output signals are further associated with a systematic offset of the plurality of image processing circuit channels. ### Claim 11 (depends on 1) The imaging system of claim 1, wherein the plurality of image sensor signals comprise a plurality of photodiode currents. ### Claim 12 (depends on 1) The imaging system of claim 1, wherein the plurality of proxy circuit channels do not receive any input signals. ### Claim 13 (depends on 1) The imaging system of claim 1, wherein the plurality of proxy circuit channels comprise a plurality of inputs biased to a DC voltage level. ### Claim 14 A method of image processing, the method comprising: processing a plurality of image sensor signals to generate a plurality of analog output signals using a plurality of image processing circuit channels, wherein the plurality of image processing circuit channels have a substantially similar circuit topology to one another; generating a plurality of analog proxy output signals associated with a common-mode noise of the plurality of image processing circuit channels using a plurality of proxy circuit channels, wherein the plurality of proxy circuit channels have a substantially similar circuit topology to one another and to the plurality of image processing circuit channels; generating a common mode noise reduction signal based on the plurality of analog proxy output signals; and generating one or more output signals based on a difference between the common-mode noise reduction signal and one or more of the plurality of analog output signals. ### Claim 15 (depends on 14) The method of claim 14, wherein generating the common mode noise reduction signal comprises averaging digital representations of the plurality of analog proxy output signals using a processor. ### Claim 16 (depends on 15) The method of claim 15, wherein generating the one or more output signals comprises subtracting the common-mode noise reduction signal from digital representations of the plurality of analog output signals. ### Claim 17 (depends on 15) The method of claim 15, further comprising: multiplexing between the plurality of analog output signals and the plurality of analog proxy signals using a multiplexer; and amplifying an output of the multiplexer to generate an amplified signal using an amplifier; converting the amplified signal to a digital output signal using an analog-to-digital converter; and providing the digital output signal to an input of the processor. ### Claim 18 (depends on 17) The method of claim 17, further comprising receiving digital representations of the plurality of analog output signals and the plurality of analog proxy signals in a serial data stream at the input of the processor. ### Claim 19 (depends on 14) The method of claim 14, further comprising: generating a reference voltage using a reference voltage generation circuit; and processing the plurality of image sensor signals based in part on the reference voltage; and providing the reference voltage to the plurality of proxy circuit channels. ### Claim 20 (depends on 14) The method of claim 14, further comprising biasing a plurality of inputs of the plurality of proxy circuit channels to a DC voltage level.