Junction temperature of CMOS electronics cooled by a regenerative cryocooler

Abstract

The optimal operation of cryo-CMOS electronics requires accurate knowledge of the junction temperature, which may be derived from the design parameters of the mechanical cryocooler and cryospace. Research on the subject has been mostly restricted to limited examples of coupled cryocooler-cryocomputer operation with little quantitative analysis. Here, we develop and experimentally validate an analytical relation between the junction temperature and the parameters of the cryogenic system for the steady-state. For validation, a printed circuit board was placed into the cryospace and cooled to 173 K using a regenerative cryocooler based on the reversed Stirling cycle. The junction temperature was measured in five experiments as a function of five different input clock frequencies. The analytical relation for the junction temperature showed good accuracy with the coefficient of variance of ±2%, the mean biased error of –2%, and the determination coefficient of 0.92. The result of this work permits determining accurately the steady-state junction temperature of a cryo-CMOS electronics in a wide range of cryogenic temperatures for different types of cryocoolers.