High CMRR instrumentation amplifier for biomedical applications

A new low-voltage single-power high CMRR and PSRR instrumentation amplifier is developed for biomedical applications. The proposed circuit uses a new structure to solve the conventional circuitspsila problems. Under similar conditions for comparison, the simulation results show the proposed circuits have better performances than conventional circuits. Besides, we also present a level shifting circuit for biomedical applications. The overall proposed circuits by HSPICE using UMC 0.18 um CMOS technology achieve a very high CMRR up to 160 dB and PSRR up to 110 dB at 1.8 V single power supply.

1. Introduction

Recording the biomedical electronics is one of the challenges in a biomedical electronics detection system, because the biomedical signal has a very weak amplitude and low frequency, usually of few milli-volts or less and the frequency below 1 KHz [1]. The biomedical electronics detecting system is shown in Fig. 1, which consists of electrodes, amplifier, LPF, Sample and hold (S/H) and ADC. Figure 1 The biomedical electronics detecting system blocks