非制冷红外探测器读出电路的非均匀性研究

对于长线列的非制冷红外探测器组件, 不同探测元之间的非均匀性是衡量电路设计的关键指标. 为了实现长线列非制冷红外探测器的高性能读出, 本文设计了一种基于电流镜方式的非制冷红外探测器160线列读出电路, 电路由电流镜输入模块、电容负反馈互导放大器模块及相关双采样输出模块组成. 电路采用0.5 μm工艺制作完成. 通过合理设置电路中MOS管的参数和布局电流镜版图, 电路的非均匀性有了明显地改善. 通过测试, 电路的非均匀性小于1%, 器件总功耗约为100 mW, 并具有良好的低噪声特性, 输出噪声小于1 mV, 输出摆幅大于2 V. 该电路与160线列非制冷红外探测器互连后, 能较好地完成红外信号的读出, 在积分时间为20 μups的情况下, 器件的响应为0.294 mV/Ω, 整体性能良好. 该电路的研制对超长线列的非制冷红外冷探测器读出电路研制奠定了重要的技术基础.

Non-uniformity study on readout circuit for uncooled IR detector

For long line uncooled infrared detectors, the non-uniformity of different detecting elements is the key parameter in measuring the circuit performance. So far there have been few research reports in this area. Most uncooled infrared detector circuits require corresponding blind detector for readout circuit design, which increases the complexity of uncooled infrared detector. In addition, the performances of these circuits need to be further improved in practical applications. In order to achieve high performance readout of the long line uncooled infrared detectors, a kind of 160 element readout circuit based on current mirror is designed in this paper. The readout circuit is composed of current mirror input part, capacitor feedback transimpedance amplifier (CTIA), and correlated double sampling (CDS) output circuit. The circuit is fabricated by using the 0.5 micron technology. The non-uniformity of circuit is obviously improved by reasonable parameter setting and current mirror circuit layout. Transconductance amplifier CTIA with capacitance negative feedback is used in the circuit. The integral capacitor consists of three capacitors whose capacitances are 10 pF, 20 pF and 20 pF respectively, thus the circuit can realize different integration capacitances, which forms different magnifications. The circuit can meet different response rates of uncooled detectors. Folded-cascode structure is adopted as the CMOS differential amplifier. The open loop gain is over 80 dB. This single-state folded-cascode construct can overcome the two-stage amplifier’s disadvantages, which easily leads to oscillations. The CDS N SF (source follow) and P SF are adopted as the circuit output, the output swing can easily be greater than 2 V. On average, the CDS N SF and P SF power consumptions are very low. So the total power consumption of 160 line circuit is lower than 100 mW. In the test, the non-uniformity of the readout circuit decreases from 10% to 1%. This result is in accordance with simulation result on non-uniformity. The other test results of total power consumption and the output amplitude also agree with simulation results. The readout circuit has good noise characteristics and the output noise is lower than 1 mV. When the readout circuit and uncooled infrared detector are connected, the infrared signal can be well read out. When the integration time is 20 μups, the device response is 0.294 mV/Ω. The overall system performance is very good. This circuit design based on current mirror has laid the technical foundation for developing readout circuit of the very large scale uncooled infrared detector in the future.