05965871 is referenced by 139 patents and cites 5 patents.

An active pixel sensing structure includes an array of pixel unit cells each of which an adapted to alternate between a light sensing mode wherein the cell outputs an image signal and a reset mode wherein the cell outputs a reset signal. The image signal is proportional to light incident on the cell, and the reset signal is proportional to a predefined reference potential. An improved readout circuit according to the present invention includes a first sample and hold component for receiving and storing the image signal, and second sample and hold component for receiving and storing the reset signal. A signal amplifier is provided for each sample and hold component. A switching circuit is operable between a first mode and a second mode. In the second mode, the first and second sample and hold components are operatively decoupled from the corresponding signal amplifiers while input terminals of the signal amplifiers are connected to a source of predetermined reference potential. With the switching circuit in the second mode, fixed pattern noise (FPN) attributable to the amplifiers is determined. With the switching means in the first mode, a voltage, D2, is determined across outputs of the signal amplifiers. The voltage, D2, is proportional to a voltage equal to the difference between the image signal and the reset signal plus the FPN voltage. A processing means subtracts the voltage, D1, from the voltage, D2, to develop a signal proportional to the light detected by the cell.

Title
Column readout multiplexer for CMOS image sensors with multiple readout and fixed pattern noise cancellation
Application Number
8/964924
Publication Number
5965871
Application Date
November 5, 1997
Publication Date
October 12, 1999
Inventor
Wei Li
Fremont
CA, US
Li yen Shih
Danville
CA, US
Zhongxuan Zhang
Fremont
CA, US
Zhimin Zhou
Santa Clara
CA, US
Agent
Justin Boyce
Oppenheimer W Donnelly
Claude Hamrick
Assignee
PixArt Technology
CA, US
IPC
H01L 27/02
H01L 27/14
G11C 19/28
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