S-Band Low-Noise HTS Filtering Receiver Front-End Subsystem Using Balanced-to-Unbalanced Structure for Radio Astronomy Application

A novel S-band balanced-to-unbalanced low-noise filtering receiver front-end subsystem is proposed in this paper. The design employs a differential input, single-ended output (DISO) receiver architecture to mitigate common-mode (CM) noise in the system. The differential receiver and filtering functions are achieved with minimal loss using a wideband high-temperature superconducting (HTS) filtering balun. The circuit is integrated with a cryogenic low noise amplifier (LNA) through optimized interconnects and package design. Test results at an ambient temperature of 15 K demonstrate an in-band gain of 31 dB and an equivalent noise temperature of 19 K, highlighting the system's potential for radio astronomy applications.