Cryogenic Receiver Front-End for Mobile Base Stations

This paper presents the fundamental configuration and characteristics of an experimental cryogenic receiver front-end (CRFE) for the 2-GHz band mobile base stations. The CRFE comprises a high-temperature superconducting filter, a cryogenically-cooled low-noise amplifier, and a highly-reliable compact-sized cryocooler. Major characteristics of the proposed CRFE are a center frequency of 1.95 GHz, passband width of 20 MHz, sharp selectivity of 20 dB/100 kHz, 1.4-dB ripple, 31.3-dB average passband gain, and average passband equivalent noise temperature of 47.9 K, all measured at 70 K. The CRFE weighs 19 kilograms and occupies 35 liters. Random failure of the cryocooler is also evaluated by a continuous operation test using four identical ones simultaneously. The cryocooler used in the CRFE has a high reliability level of over five years of continuous maintenance-free operation.