双色红外焦平面数字读出电路研究

Research on Dual-Color Digital ROIC for IRFPA

摘要:

设计了一款中、长波双色应用的数字化红外焦平面读出电路。由于双色红外焦平面器件在注入电流及动态输出阻抗上存在着数量级的差异,同时双波段均要求高灵敏度,因此读出电路需要在有限像元面积内实现双输入级的结构设计和大动态范围。电路采用基于直接注入型输入级的脉冲频率调制结构,设计电荷复位单元代替传统电压复位结构,可降低可探测的电荷分辨率,并改善由复位遗失电荷带来的非线性影响,同时电路设计了20bit混合结构的计数器,满足电路大电荷容量和低功耗的要求。仿真结果表明,实现的最小电荷分辨率为692e-,对应电荷容量为7.2×10⁸e-,双波段探测线性度均高于99.8%,在中、长波典型应用情况下功耗分别为3.03,6.66μW。

Abstract:

In this study, we designed an infrared focal plane array (IRFPA) digital readout integrated circuit (ROIC) for medium/long-wave (MW/LW) dual-color applications. Owing to the variation in the magnitude of the injection current, dynamic output impedance of dual-color IRFPA devices, and the high sensitivity required for both bands, the structural design of two input stages and a large dynamic range must be achieved within the limited pixel area of the ROIC. Therefore, the proposed circuit adopted a pulse frequency modulation (PFM) structure based on a direct injection (DI) type input stage and a charge reset unit to replace the traditional voltage reset structure, reducing the detectable charge resolution and improved the nonlinear effect caused by the reset lost charge. We designed a 20-bit hybrid structure counter to satisfy the large-charge capacity and low-power consumption requirements of the circuit. Simulation results demonstrated that the minimum charge resolution was 692e-, corresponding to a charge capacity of 0.72Ge. The dual-band detection linearity exceeded 99.8%, and the power consumption was 3.03/6.66μW in typical MW/LW applications.