A wideband readout charge amplifier for superconducting nanowire single photon detector

Abstract This paper represents a 2.5 GHz gain-bandwidth product readout amplifier. It employs three folded cascode core units and negative feedback paths. The feedback path includes capacitors and resistors. It can reduce input resistance and isolate the parasitic photodiode capacitance. To reduce the capacitance of the long wire, it is integrated with a superconducting nanowire single photon detector and amplifies signals in a cryogenic working environment. After the measurement of this integrated circuit, it can convert a 1 GHz 1 uA sinusoid signal into a 10 mV voltage signal under a cryogenic condition. The total chip is fabricated in a 180 nm SMIC under a supply voltage of 1.2 V with a power consumption of 60 mW. Its gain is 2.976 uV/e.