Highly compact and efficient JTRS radios using superconductor microelectronics - a quantum leap in performance: the cryopackage

Superconductor microelectronics (SME) are rapidly redefining the state-of-the-art in wireless RF performance. SME-based digital RF subsystems, enabled by compact cryocoolers, have the potential to achieve all JTRS objective requirements (not just the thresholds) for performance, SWaP, and Cost as an Independent Variable (CAIV) targets for clusters 1, 3 and 4. Compact cryo-packaging is the key to deploying SME-based digital RF subsystems in JTRS and other wireless radio systems. A compact cryocooler provides the cryogenic environment for the superconductor multi-chip modules (MCM). The cryo-package (comprising the MCM and compact cryocooler) includes the mechanical and electrical interfaces to the JTRS radio. For example, a single SME-based digital RF subsystem provides a 10-channel full-duplex transceiver in less than 500 in³, 30 lbs, and 150 watts; and an availability (up time) on the order of 99.998%. This paper discusses all aspects of cryopackaging, which include compact closed-cycle refrigerators or cryocoolers, methods of building and cooling superconductor multi-chip modules, managing thermal loads of input-output leads between warm ambient temperature electronics and cold superconductor electronics, and electromagnetic shielding.