Template models of silicon carbide JFETs and their practical applications in high-temperature analog chip design problems in LTspice environment

Abstract

Modern achievements of leading microelectronic firms in the field of designing operational amplifiers (Op-Amp) and their functional units based on silicon carbide, designed for operation in the temperature range up to 300-600 °C, are analyzed. Numerical values of the parameters of existing high-temperature operational amplifiers, created for space missions of NASA Research Center named after Gallen, on the open-circuit voltage gain, the systematic component of the zero offset voltage, the frequency of single gain, the maximum rate of increase of the output voltage, the coefficient of attenuation of input in-phase signals and the coefficient of suppression of interference on the power supply rails, as well as information on the experimental characteristics of Op-Amps during long-term operation at high temperatures and exposure to radiation. To model circuits at temperatures up to 450 °C, template models of SiC transistors (TM) have been developed using the template modeling technique, in which constant model parameters are replaced by fractional-rational functions (Padé approximation), allowing to describe more accurately the physical processes in JFETs without violating the nature of their changes. For the freely distributable modeling environment LTspice the instruction for application of the TM is developed. Circuit solutions of high-temperature basic analog functional units realized on the basis of silicon carbide field-effect transistors are considered. The basic characteristics of SiC source repeaters, SiC differential stages and the simplest SiC operational amplifiers based on them at temperatures of 25 °C and 452 °C are investigated. The obtained results are recommended to be used in the design of high-temperature operational and instrumental amplifiers in space instrumentation, deep well drilling, automotive industry, nuclear reactors, etc.