A high-precision readout circuit for MEMS sensors operating across a wide temperature range.

Abstract

The detection of signals from Micro-Hemispherical Resonator Gyroscopes constitutes a crucial element of their control systems. This paper presents a fully differential transimpedance amplifier (TIA) designed for the detection of small currents in microsensors. The proposed amplifier features a two-stage architecture and allows for adjustable gain through manipulation of the feedback resistance value. To ensure performance across the full temperature range, we have developed a high-precision bandgap reference (BGR) that incorporates nonlinear term cancellation and multisectional curvature compensation techniques. The stable reference current provided by the BGR is critical for maintaining the accuracy of our readout circuits. The programmable gain amplifier is implemented using 180 nm Bipolar-CMOS-DMOS technology. The simulation results indicate that the proposed amplifier attains a high gain and provides flexible gain adjustment capabilities. Measurement results show that our proposed TIA achieves a capacitance resolution below 1 aF in gyroscope front-end readout applications and can operate normally within a temperature range of -40 to 65 °C.