Abstract
This paper presents a novel pixel structure of readout integrated circuit (ROIC) for infrared focal array plane (IRFPA). The pixel can operate in the linear-logarithmic mode to reach high dynamic range. The pixel is based on the buffered direct injection (BDI) as the input cell. The logarithmic response is realized by adding two additional diode-connected MOSFETs. The pixel can automatically switch between the linear and the logarithmic mode. The threshold voltage of the mode-switching is controlled by a given voltage. A linear-logarithmic test chip consisting of a small pixel array has been designed and fabricated using Global Foundry 0.18 μm 1P6M process. A medium wave infrared detector has been hybridized to the chip. The experimental results show that the logarithmic sensitivity is 86 mV/dec. The dynamic range of the chip is higher than 137 dB and the dynamic range of the chip with a detector is greater than 102 dB.
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