Television – Camera – system and detail – Solid-state image sensor
Patent
1997-03-19
2000-02-29
Ho, Tuan
Television
Camera, system and detail
Solid-state image sensor
348294, H04N 314
Patent
active
060315709
ABSTRACT:
An image acquisition and processing system that can eliminate or reduce the effects of offset voltage and threshold voltage is disclosed. The system contains a plurality of operational amplifiers each is used in an integrator. Each of the operational amplifiers has an offset voltage. The output of the integrator is sampled twice by a dual sampling circuit, one when connected to a photo-sensor and the other when not connected to the photo-sensor. The difference between the two samplings cancels out the effect of the offset voltage. The system also contains a plurality of transistors used as source follower. Each of the transistors is connected to an output terminal of the dual sampling circuit. These transistors have different threshold voltages. The output of a transistor is sampled. A predetermined voltage is then applied to the transistor and the output is again sampled. The difference between these two samples cancels out the effect of the threshold voltage. The effect of the predetermined voltage can be canceled out by taking a second difference between the twice sampled output originated from two transistors.
REFERENCES:
patent: 4575638 (1986-03-01), Okumura
patent: 5060071 (1991-10-01), Ino
patent: 5146339 (1992-09-01), Shinohara et al.
patent: 5231503 (1993-07-01), Nagatake et al.
patent: 5736886 (1998-04-01), Mangelsdorf et al.
Chen Datong
Shyu Tai Ching
Yang Hongli
Ho Tuan
Nguyen Luong
OmniVision Technologies Inc.
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