An SOI-CMOS low noise chopper amplifier for high temperature applications

This paper presents the principle and design of an SOI-CMOS low noise chopper amplifier for electronic data acquisition system in down-hole-drilling application that operates at the high temperature (>170 oC) regime. The chopper amplifier is designed to have three-stages where the first stage is a folded cascade. A commercially available 1-μm SOI-CMOS technology was chosen. Simulations showed that the input-referred noise of the chopper amplifier is about 25.6 nV/sqrt(Hz) at 700 Hz with a total current consumption of 5.496 mA. Measurements proved that the chopper amplifier is able to work up to 300 oC.