一种应用于非制冷焦平面读出电路的?非线性辐射补偿型ADC设计

An ADC with Substrate Temperature Compensation Applied to Uncooled Infrared FPA Readout Circuit

针对非制冷红外探测器系统,设计了一种具有辐射非线性补偿功能的ADC结构。首先分析了辐射非线性对微测辐射热计的特性的影响,利用非线性单斜率ADC(Nonlinear Single-Slope ADC)对非线性辐射引起的微测辐射热计的特性的变化进行补偿,实现ROIC的输出信号的线性化。使用双非线性斜波发生器的模数转换较普通单斜率模数转换节省了近一半的时间,提高了探测器帧频。该ROIC已在0.5??m CMOS工艺下成功流片,并应用了到阵列大小为320×240的非制冷微测辐射热计焦平面上。测试结果表明:目标温度变化640K时,输出信号呈线性(NL=0.94%),数字码有效利用率大于96%。该ROIC在大阵列、小体积的非制冷红外探测器上有着广泛的应用。

This paper describes a new ADC architecture with nonlinear radiation compensation for uncooled microbolometer detector. The influence of responsivity on the nonlinear radiation is evaluated. Numerical simulation and measurement of the proposed ROIC architecture demonstrate high quality of signal over wide target temperature range with using nonlinear single-slope ADC. A 320 × 240 uncooled microbolometer focal plane array （FPA） based on the proposed circuit was implemented on silicon using 0.5 μm CMOS technology. The measurement data show that the maximum difference of the nonlinear is only 0.94% and the utilization rate is more than 96% over 640 K target temperature change. Thus it is ideally suited for low-cost, low-power, and low-weight production applications.