Electrical pulse counters – pulse dividers – or shift registers: c – Charge transfer device – Particular input or output means
Reexamination Certificate
1995-12-05
2001-06-05
Munson, Gene M. (Department: 2811)
Electrical pulse counters, pulse dividers, or shift registers: c
Charge transfer device
Particular input or output means
C257S217000, C257S239000
Reexamination Certificate
active
06243434
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to image sensor devices and more particularly to charge coupled devices.
BACKGROUND OF THE INVENTION
Without limiting the scope of the invention, its background is described in connection with charge coupled device (CCD) image sensors, as an example. Essential to good low noise performance of a CCD image sensor is the charge detection amplifier which converts charge stored at an individual photo site into a signal of adequate magnitude for further processing.
The most popular charge detection concept in CCD sensors is based on a floating diffusion circuit. A typical prior art charge detection amplifier consists of a floating diffusion detection node and an amplifier circuit. See Hynecek, J., “Method of Making Top Buss Virtual Phase Frame Interline Transfer CCD Image Sensor”, U.S. Pat. No. 5,151,380, issued Sep. 29, 1992. The charge detection node is a conventional gated floating diffusion structure typically used with virtual phase CCDs and has an externally driven reset gate.
SUMMARY OF THE INVENTION
Generally, and in one form of the invention, the image sensor charge detection amplifier has a charge storage well, a charge sensor for sensing charge levels in the charge storage well, a charge drain adjacent to the charge storage well, and charge transfer structures for transferring charge from the charge storage well to the charge drain.
This invention provides several advantages. One advantage is that a complete reset of the structure is accomplished. There is no charge left in the detection well after the reset. Another advantage is that complete reset means no kTC noise. This leads to lower noise performance and simpler signal processing. Another advantage is the non destructive charge readout. Since no charge is lost in the detection node, it can be transferred to another CCD stage. Another advantage is that this invention is a smaller structure than prior structures because the MOS transistor and the detection well are integrated into one device. The smaller structure leads to higher sensitivity which is also desirable. Another advantage is that additional internal or external circuits can be easily connected to this detection amplifier to increase the gain, to obtain gamma correction, or to obtain nonlinear signal compression which extends the dynamic range.
REFERENCES:
patent: 4074302 (1978-02-01), Brewer
patent: 4090095 (1978-05-01), Herrmann
patent: 4668971 (1987-05-01), Hynecek
patent: 4984045 (1991-01-01), Matsunaga
patent: 5357128 (1994-10-01), Shinji
patent: 5436476 (1995-07-01), Hynecek
patent: 5546438 (1996-08-01), Hynecek
Brady III Wade James
Munson Gene M.
Stewart Alan K.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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