延伸波长InGaAs焦平面用低失调电压输入级电路研究

Research of Low-offset Input Stage for Extended-Wavelength InGaAs FPA

摘要:

截止波长为2.5μm的延伸波长InGaAs探测器在航天航空遥感等领域有着重要应用。由于晶格失配，相同温度下它的暗电流比截止波长为1.7μm的常规InGaAs探测器高2~3个数量级。从焦平面的耦合接口出发，研究了一种新型的Autozero输入级电路，通过大幅降低输入失调电压来减小耦合接口处延伸波长InGaAs器件的偏置电压和暗电流。在CTIA采样反馈回路中设计了一种双电源电压工作的反相器，通过消除开关管两端电压差抑制了非理想开关漏电对采样失调电压的影响。分析了输入端采样电容和失调电压的关系，优化设计后仿真实现了16.5μV的低失调电压。

Abstract:

Extended-wavelength InGaAs detector with 2.5μm cut-off wavelength plays an important role in space remote sensing and so on. As a result of the lattice mismatch, the dark current of extended-wavelength InGaAs is 2～3 orders of magnitude higher than 1.7μm-wavelength InGaAs at the same temperature. In this paper, a new-type low input-offset-voltage autozero input stage circuit was developed in the coupling interface of FPA, which aims to reduce the bias voltage and dark current of extended-wavelength InGaAs detectors. A new inverter working in two kinds of supply voltages wass designed in CTIA sampling feedback loop to restrain the influence of switch leakage on the sampled offset voltage. The relationship between sampling capacitance and offset voltage was analyzed. According to the results of simulation, the offset voltage is reduced to 16.5μV after optimization.