A Readout Circuit with Current-Compensation-Based Extended-Counting ADC for 1024×768 Diode Uncooled Infrared Imagers

This paper presents a low-power readout circuit with 14-bit column-level extended-counting ADC for 17μm-pitch 1024 × 768 silicon diode uncooled infrared imagers. The ADC's coarse conversion adopts a current-mode DAC to feedback charge into a CTIA-based integrator during integration and the fine conversion is implemented by a SAR ADC after integration. A current self-compensator and a modified DAC are proposed to reduce more than 50% power of the overall integrator compared with conventional structure. The 1024 × 768 readout circuit has been fabricated in the 0.18 μΜ 1P5M CMOS process. Power consumption of the readout circuit is 104mW and each column ADC only consumes 15μW. Simulation results show that the RMS noise of the readout circuit is 0.9LSB and nonlinearity is 0.06% at 30fps.