A Chopper Modulation Instrumentation Amplifier with Micro-current and Current Feedback

Abstract

The invention belongs to the technical field of amplifiers, and particularly relates to a current feedback chopper modulation instrument amplifier working under a micro quiescent current. The amplifier consists of a blocking condenser, a current feedback chopper amplifier, an N-bit mismatch compensation capacitor array, a ripple canceling circuit, a biasing circuit and a clock frequency dividing circuit. The microcurrent and current feedback chopper modulation instrument amplifier has the characteristics of alternating current coupling, high input impedance, ultra-low offset voltage, low noise, high common mode rejection ratio, high power supply rejection ratio, micro-power consumption and the like; the circuit is particularly suitable for a wearable health monitoring system biopotential acquisition circuit adopting dry electrodes, and can eliminate semi-potential imbalance between electrodes in a rail-to-rail mode. The simulation result of one embodiment of the invention shows that the common-mode rejection ratio of the instrument amplifier is greater than 120 dB, the equivalent input impedance is greater than 500 M Ohm, and the noise energy efficiency factor NEF is equal to 4.5.

Description

technical field [0001] The invention belongs to the technical field of amplifiers, in particular to an instrument amplifier for accurately measuring weak signals. Background technique [0002] An instrumentation amplifier is an amplifier that can accurately amplify the voltage difference between two input ports (input differential signal) while suppressing the common-mode signal of the input port. It has high input impedance, high common-mode rejection ratio, high power supply rejection ratio, and low Offset, low offset drift, low noise and so on. It can be used to measure bioelectrical signals, such as EEG signals, ECG signals and EMG signals. [0003] The wearable health monitoring system needs to collect the physiological parameters of the human body without affecting people's daily life, and it needs to meet the requirements of portability, long-term and compatibility. Bioelectrodes are indispensable components for measuring bioelectrical signals. In order to improve c...

AI Technical Summary

Problems solved by technology

The elimination of electrode imbalance is mainly realized through the offset feedback loop or capacitor DC blocking: the offset feedback loop is difficult to eliminate the electrode offset above 100 mV, and will greatly increase the power consumption, which is not suitable for dry electrodes with large electrode offset; The input capacitor used for DC blocking will generally reduce the input impedance of the circuit, and the mismatch of the input capacitor will directly reduce the CMRR of the circuit

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