Design of TIA for Room-Temperature HgCdTe Diode Based on Auto-Zero Technology

This paper reports on a transimpedance amplifier (TIA) designed specifically for room-temperature mercury cadmium telluride (HgCdTe) photovoltaic diodes. Based on auto-zeroing technology, this design successfully reduces the op amp’s equivalent input offset voltage to 7.6 μV, effectively suppressing the detector’s dark current induced by the offset voltage, thus resolving a core challenge in high-precision infrared readout circuits near zero bias. Built on a 0.18 μm TSMC, 3.3 V CMOS process, this technology uses an auxiliary input to correct the offset voltage and employs linear components and a negative feedback loop to suppress nonlinear distortion. Furthermore, the design ensures a highly symmetrical layout of the op amp and guard rings within the layout, optimizing the system structure and reducing offset and noise. The on-chip area is approximately 0.16 mm2. Under 3.3 V supply voltage and room temperature, the amplifier achieves an effective input-referred noise of 8.3 μV within a 1-400 Hz bandwidth. The offset voltage before auto-zero is 480 μV, and it decreases by 98.4% after auto-zeroing. A photovoltaic-type HgCdTe photodiode is connected across the auto-zero operational amplifier with added bias voltage, resulting in an output swing improvement of over 0.55 V. The design exhibits good linearity and effectively suppresses the increase in dark current caused by the offset voltage in the HgCdTe photodiode. A comparison between simulation and measurement results confirms the design’s accuracy and validates the effectiveness of the auto-zero technique under real-world conditions.