US 12,294,802 B2
Low power event driven pixels with active difference detection circuitry, and reset control circuits for the same
Andreas Suess, San Jose, CA (US); and Shoushun Chen, Shanghai (CN)
Assigned to OMNIVISION TECHNOLOGIES, INC., Santa Clara, CA (US)
Filed by OMNIVISION TECHNOLOGIES, INC., Santa Clara, CA (US)
Filed on Jul. 27, 2022, as Appl. No. 17/875,244.
Prior Publication US 2024/0040283 A1, Feb. 1, 2024
Int. Cl. H04N 25/771 (2023.01); H03F 3/16 (2006.01); H04N 25/42 (2023.01); H04N 25/709 (2023.01); H03K 19/20 (2006.01)
CPC H04N 25/771 (2023.01) [H03F 3/16 (2013.01); H04N 25/42 (2023.01); H04N 25/709 (2023.01); H03K 19/20 (2013.01)] 32 Claims
OG exemplary drawing
 
1. An event driven pixel, comprising:
a photosensor configured to generate photocurrent in response to incident light received from an external scene;
a photocurrent-to-voltage converter coupled to the photosensor to convert the photocurrent to a voltage;
a difference circuit coupled to the photocurrent-to-voltage converter, wherein the difference circuit includes a source follower transistor, and wherein the difference circuit is configured to (a) generate a reference signal at a gate of the source follower transistor based at least in part on the voltage and (b) output a difference signal from the event driven pixel in response to assertion of a row select signal applied to a row select transistor of the difference circuit, wherein the difference signal is a result of a comparison between (i) the reference signal and (ii) the voltage at a moment of assertion of the row select signal; and
a reset control circuit coupled to the difference circuit and configured to:
initialize the difference circuit in response to assertion of a global reset signal applied to the reset control circuit, and
reset the difference circuit in response to a combination of (a) assertion of the row select signal applied to the reset control circuit and (b) assertion of an acknowledge signal applied to the reset control circuit when the difference signal indicates a change in the voltage greater than a threshold amount.