A current feedback type instrument amplifier with a high common-mode rejection ratio

Abstract

The invention provides a current feedback type instrument amplifier with a high common-mode rejection ratio. The current feedback type instrument amplifier comprises an input transconductance amplification circuit, an input transconductance balance circuit, a feedback transconductance amplification circuit, a feedback transconductance balance circuit and a transconductance capacitor (Gm-C) high-pass filter circuit. According to the invention, two same transconductance amplifiers are respectively used as an input stage and a feedback stage of the circuit; an input transconductance balance circuit structure formed by a sleeve type operational amplifier is adopted to balance differential current input into the transconductance amplifier; and a feedback transconductance balance circuit structure composed of two stages of operational amplifiers is adopted to balance the differential current of the feedback transconductance amplifier, so that the influence caused by mismatch of the differential current is eliminated, at the same time, the current Io flowing through the resistor R2 is forced to be equal to the current Ii of the resistor R1, and the high common-mode rejection ratio is realized. A high-pass filter composed of transconductance capacitors is adopted to set a high-pass pole, so that the human body noise and the direct-current imbalance are isolated, the circuit noise is effectively reduced, and the circuit area is reduced.

Description

technical field [0001] The invention belongs to the field of analog integrated circuit design, and in particular relates to the design of a current feedback instrument amplifier circuit with high common-mode rejection ratio. Background technique [0002] With the rapid development of wearable electronic products and Internet of Things (IoT) technology, more and more medical monitoring instruments are also adopting low power consumption, miniaturization, and portable circuit design solutions, such as electrocardiogram (ECG) signal acquisition and analysis system. figure 1 For a typical instrumentation amplifier application scenario. patients can pass figure 1 The external sensor of the portable ECG signal acquisition system shown collects ECG signals, and accurately amplifies them through the IA described in this article, then processes the analog signals through the system, and finally uploads the results to the "cloud", and then sends them to After the hospital doctor co...

AI Technical Summary

Problems solved by technology

This three-op-amp instrumentation amplifier relies heavily on resistor matching, and any resistor mismatch can have a big impact on the common-mode rejection performance of the entire circuit

[0005] Problems such as low common-mode rejection ratio (CMRR) and poor noise performance in the existing IA circuit design

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