Design and Noise Analysis of a Novel Auto-Zeroing Structure for Continuous-Time Instrumentation Amplifiers

Abstract

Abstract-This paper introduces a low-noise, low-power amplifier for high-impedance sensors. An innovative circuit using an auto-zeroed architecture combined with frequency modulation to reject offset and low-frequency noise is proposed and analysed. Special care was given to avoid broadband noise aliasing and chopping in the signal path, and to minimize both the resulting equivalent input offset voltage and equivalent input biasing current. The theoretical noise analysis of the proposed topology covers most of the noise sources of the circuit. Simulations show that the input-referred noise level of the circuit is 13.4nV / √ Hz for a power consumption of 85µA with a power supply from 1.8V to 3.6V.