A Low-power Continuous-Reset CMOS Charge-Sensitive Amplifier for the Readout of Solid-State Radiation Detectors

In this paper, the design of a low-power continuous-reset CMOS charge-sensitive amplifier (CSA) is presented. The proposed CSA is intended for capacitive sensor readout circuits, in particular, interface circuits for solid-state detectors used in medical imaging and X-ray spectroscopy. A proof-of-concept interface circuit is designed and fabricated in a 0.13-μm CMOS process and consists of the proposed CSA, a pole-zero cancellation circuit, and a second-order semi-Gaussian programmable pulse shaper. Measurement results show that the conversion gain of the CSA and the pulse shaper are about 8.8 and 13.9 mV/fC, respectively. The CSA can accept signals of both polarities and the charge integration is linear from about -9 to 6 fC. The measured equivalent noise charge of the CSA is about 111 e̅-rms. The CSA occupies 0.0021 mm² of silicon area and consumes only 37.5 μW from dual supply voltages of 0.9 and 1.2 V.