A high-gain, low-noise switched capacitor readout for FET-based THz detectors

A noise-efficient readout interface designed in a 150nm standard CMOS technology for a FET based THz radiation detector is presented. The interface is able to detect μV-range rectified signal from the FET detector, amplifying it by 70 dB gain. A multistage switched-capacitor (SC) readout channel employing chopper modulation is exploited so as to remove 1/f noise and obtain repeatable gain and frequency response. The characterization results show that the channel is able to achieve a maximum voltage responsivity of 470 kV/W and a minimum Noise Equivalent Power (NEP) of 480 pW/√Hz at 370 GHz source frequency. The total power consumption of the readout interface is 200 μW, while the channel area, comprising the interface and on-chip antenna, is 0.375 mm
²
, making it suitable for implementation in pixel array configuration for THz imaging.