Junction temperature of CMOS electronics cooled by a Stirling cryocooler

Abstract

This case study addresses the practical challenges associated with operating cryo-CMOS electronics. Previous research has been largely confined to impractical liquid cryogen cooling and the few under-reported examples of implementing electric cryocoolers. This study further clarifies the operation of cryo-CMOS devices cooled by electric cryocoolers. It develops and experimentally validates an analytical relation between the junction temperature and the parameters of a cryogenic system. To validate this relationship, we placed a printed circuit board in a thermal chamber, cooled it to 173 K using a Stirling cryocooler, and varied input clock frequencies. The measured values of the junction temperature were compared with calculations, which showed good prediction accuracy with a coefficient of variance of ±2%, a mean biased error of −2%, and a determination coefficient of 0.92. In addition, the measurements provided evidence for a multi-fold increase in the clock frequency of cryo-CMOS electronics. The results of this study help estimate accurately the steady-state junction temperature of cryo-CMOS devices in a wide range of cryogenic temperatures for different types of cryocoolers.