基于分时共享方案的640×512红外读出电路设计

大规模、高集成度的红外焦平面器件是实现高空间分辨率红外成像的核心。针对高集成度的红外焦平面技术发展，文中设计了一款15 m中心距640512的红外焦平面读出电路。为提升器件信噪比和积分时间，提出了一种22四个像元分时复用积分电容共享技术方案，单元采用直接注入（DI）结构作为输入级，使得读出电路最大电荷容量可达20 Me-/像元。电路有两档电荷容量可选，可满足不同光电流信号的读出要求。为了减小噪声的注入及提高缓冲器偏置电流的精度，为信号传输链路设计了相应的偏置电路。电路仿真结果表明，电路帧频108 Hz，功耗低于110 mW，线性度可高达99.99%。电路采用了CSMC 0.18 m 1P4M 3.3 V工艺加工流片，常温测试结果显示电路工作电流正常，偏置开关可控，功能正常。

Design of 640×512 infrared ROIC based on time-sharing method

Large scale and high integration of IRFPA device is the core of high spatial resolution infrared imaging. With the development of the high integration IRFPA technology, a 640512 readout integrated circuit(ROIC) of IRFPA with 15 m pixel pitch was presented. In order to improve SNR and integration time, one technology method of 2 by 2 pixels sharing an integration capacitor was proposed and the DI architecture was chosen as the input stage, thus the maximum effective charge capacity can reach 20 Me-/pixel. And two levels of charge capacity can be chosen for the readout of different photocurrents.Moreover, current bias circuits were designed for the analog signal chain ciruit to lower the noise and improve the bias current accuracy for buffers. According to the simulation results, the circuit achieves 108 Hz frame rate, less than 110 mW and 99.99% linearity. The circuit was taped out by CSMC 0.18 m 1P4M 3.3 V CMOS process. The preliminary test results under room temperature show that the working current is normal and the bias switches can be adjusted and the circuit can work normally.