High-performance CMOS buffered gate modulation input (BGMI) readoutcircuits for IR FPA

摘要

A new CMOS current readout structure for the infrared (IR)nfocal-plane-array (FPA), called the buffered gate modulation inputn(BGMI) circuit, is proposed in this paper. Using the technique ofnunbalanced current mirror, the new BGMI circuit can achieve high chargensensitivity with adaptive current gain control and good immunity fromnthreshold-voltage variations. Moreover, the readout dynamic range can bensignificantly increased by using the threshold-voltage-independentncurrent-mode background suppression technique. To further improve thenreadout performance, switch current integration techniques,nshared-buffer biasing technique, and dynamic charging output stage withnthe correlated double sampling circuit are also incorporated into thenBGMI circuit. An experimental 128×128 BGMI readout chip has beenndesigned and fabricated in 0.8 Μm double-poly-double-metal (DPDM)nn-well CMOS technology. The measurement results of the fabricatednreadout chip under 77 K and 5 V supply voltage have successfullynverified both readout function and performance improvement. Thenfabricated chip has the maximum charge capacity of 9.5×107n electrons, the transimpedance of 2.5×109 Ωnat 10 nA background current, and the arrive power dissipation of 40 mW.nThe uniformity of background suppression currents can be as high as 99%.nThus, high injection efficiency, high charge sensitivity, large dynamicnrange, large storage capacity, and low noise can be achieved In the BGMIncircuit with the pixel size of 50×50 Μm2. Thesenadvantageous characteristics make the BCMI circuit suitable for variousnIR FPA readout applications with a wide range of background currents