A novel method to realize automatic gain adjust for infrared readout integrated circuit

A novel method to adjust gain in CMOS infrared (IR) readout integrated circuit (ROIC) which is suitable for the application of small pixel size has been proposed in this paper. Current mirror is inserted in the pixel to adjust gain. Two comparators have been added outside of the pixel and provide the decision to select different gains. Adjustable gain makes the design of following signal process circuit easier and allows long integration time to increase SNR. With this method of automatic gain adjust, ROIC can deal with the current that varies from 40nA to 300nA, with the integration capacitor of 2pF and the integration time of 40/spl mu/s. An experimental 4/spl times/4-pixel ROIC has been designed and it will be fabricated with 0.5/spl mu/m DPDM n-well CMOS process.

[1]  B.J. Hosticka,et al.  A high dynamic range CMOS image sensor for automotive applications , 2000, Proceedings of the 25th European Solid-State Circuits Conference.

[2]  B. Schneider,et al.  Vertically integrated sensors for advanced imaging applications , 2000, IEEE Journal of Solid-State Circuits.

[3]  Chung-Yu Wu,et al.  The design of high-performance 128/spl times/128 CMOS image sensors using new current-readout techniques , 1999, ISCAS'99. Proceedings of the 1999 IEEE International Symposium on Circuits and Systems VLSI (Cat. No.99CH36349).

[4]  Mary J. Hewitt,et al.  Overview of advances in high-performance ROIC designs for use with IRFPAs , 2000, Defense, Security, and Sensing.

[5]  Igor I. Taubkin,et al.  Infrared focal plane arrays: state of the art and development trends , 2003, Saratov Fall Meeting.

[6]  B.J. Hosticka,et al.  A CMOS photodiode array with in-pixel data acquisition system for computed tomography , 2004, IEEE Journal of Solid-State Circuits.