Television – Camera – system and detail – Solid-state image sensor
Reexamination Certificate
2004-06-16
2009-11-10
Tran, Sinh (Department: 2622)
Television
Camera, system and detail
Solid-state image sensor
C348S294000, C348S308000, C257S292000
Reexamination Certificate
active
07616242
ABSTRACT:
A system and method are disclosed to enlarge the sub-threshold current coefficient “α” of a reset transistor connected to a photodiode in an L-L (Linear Logarithmic) pixel sensor without modifying any semiconductor process parameters. In one embodiment, a coupling capacitor is introduced between the gate and source terminals of the reset transistor. The gate node of the reset transistor is kept floating and the change in its source voltage Vs is coupled to its gate voltage Vg by a certain rate with the help of the coupling capacitor. Thus, an effective change in (Vg-Vs) is made small, which is equivalent to enlarging the sub-threshold coefficient “α” In this manner, the signal gain in the logarithmic region of operation of the pixel sensor can be controlled by changing the coupling capacitance between the source and gate terminals of the reset transistor connected to the photodiode. The signal conversion gain in the logarithmic region is increased, but the gain in the linear region is unchanged. In one embodiment, the stray capacitance (which also affects the value of the enlarged “α”) present at the gate terminal of the reset transistor is externally controlled to achieve adaptive gain control of the output signal in the logarithmic region so as to obtain large output photo voltage swings even under varying light conditions. Because of the rules governing abstracts, this abstract should not be relied upon in construing the claims.
REFERENCES:
patent: 6191408 (2001-02-01), Shinotsuka et al.
patent: 6246436 (2001-06-01), Lin et al.
patent: 6512544 (2003-01-01), Merrill et al.
patent: 6903394 (2005-06-01), Agarwal
patent: 2002/0033445 (2002-03-01), Mattison
patent: 2005/0062867 (2005-03-01), Mabuchi
patent: 0828297 (1998-03-01), None
patent: 0933928 (1999-04-01), None
patent: 1187217 (2002-03-01), None
patent: WO 9953687 (1999-10-01), None
Ricquier et al., N., “Active Pixel CMOS Image Sensor with On-Chip Non-Uniformity Correction”.
Kavadias et al., S., “P8: On-chip offset calibrated logarithmic response image sensor”, pp. 68-71.
Sasaki et al., M., “P4 A CMOS Image Sensor Integrating Gamma Correction and Gain Control Functions”, pp. 52-55.
Fox et al., E., “Wide-Dynamic-Range Pixel with Combined Linear and Logarithmic Response and Increased Signal Swing”.
Ando Haruhisa
Takayanagi Isao
Jones Day
Micro)n Technology, Inc.
Pasiewicz Daniel M
Pencoske Edward L.
Tran Sinh
LandOfFree
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