A low noise and wide dynamic range preamplifier for HPGe detectors

Purpose HPGe detectors can be used for both dark matter search and neutrinoless double beta decay experiments. However, signal amplitudes of these two experiments are quite different. This paper presents the development of a wide dynamic range CMOS preamplifier for HPGe detectors, which can also be used for low light level photon detection.
Methods The structure of a dual-stage dual-gain amplifier was adopted to receive the signals with charges ranging from ~ 0.01 fC to 500 fC. A novel “pre-reset” technique has been proposed to reduce the dead time ratio for large signals. A prototype chip was fabricated and tested.
Results A minimum ENC of 43 electrons has been achieved for the high-gain channel at 77 K and the maximum charge of the input signal could be up to 500 fC for the low-gain channel, corresponding to a dynamic range above 90 dB.
Conclusions The dual-gain structure of the preamplifier and the “pre-reset” method have been successfully verified, which can be used for HPGe detectors for dark matter and neutrino experiments in the future.