A Low Noise High Input Impedance Chopper-Stabilized Biopotential Amplifier with Ripple Reduction Technique

Ankit  ADESARA; Amisha  NAIK

doi:10.48048/wjst.2021.23974

Authors

Ankit ADESARA Institute of Technology, Nirma University, Ahmedabad, India
Amisha NAIK Institute of Technology, Nirma University, Ahmedabad, India

DOI:

https://doi.org/10.48048/wjst.2021.23974

Keywords:

Biopotential amplifier, Chopper stabilization, Electrocardiogram, Noise, Ripple

Abstract

Biopotential signals are created as a result of the electrochemical activity of the many cells that comprise the nervous system, and they represent both normal and pathological organ function. These signals must be identified with extreme caution because they are surrounded by a great deal of noise when detected by sensors. This article explores a novel biopotential amplifier that incorporates the chopper stabilization technique to increase noise performance and minimize offset. However, by introducing the chopper modulator into the proposed design, the amplifier's overall input impedance was lowered, which was then increased to greater than 200 MΩ by adding the forward auxiliary path to the input branch. Additionally, the output ripple, produced due to switching activity and up-sampling, was reduced by inclusion of the R-C ripple removing block at the output of the operational transconductance amplifier (OTA). The designed architecture had a mid-band gain of 40dB with a power consumption of 9 µW and an offset of 10µV and a CMRR of 82 dB. It generated a noise of 42nV/√Hz. Also, the obtained results were compared with a conventional amplifier. The proposed design was verified by carrying out simulations using 180nm technology parameters. Cadence Virtuoso (Schematic editor), Spectre (Simulator), Symica and Magic (Layout) tools were used to complete the implementation and simulation of the proposed design.

HIGHLIGHTS

Biopotential signals are created as a result of the electrochemical activity of the many cells which must be identified with extreme caution because they are surrounded by a great deal of noise when detected by sensors
It explores a novel biopotential amplifier that incorporates the chopper stabilization technique to increase noise performance and minimize offset
By introducing the chopper modulator into the proposed design, the amplifier's overall input impedance was lowered, which was then increased to greater than 200 MΩ by adding the forward auxiliary path to the input branch
The output ripple, produced due to switching activity and up-sampling, was reduced by inclusion of the R-C ripple removing block at the output of the operational transconductance amplifier (OTA)
The designed architecture had a mid-band gain of 40dB with a power consumption of 9 µW and an offset of 10 µV and a CMRR of 82 dB. It generated a noise of 42 nV/√Hz

GRAPHICAL ABSTRACT

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