A Chopper Instrumentation Amplifier with Fully Symmetric Negative Capacitance Generation Feedback Loop and Online Digital Calibration for Input Impedance Boosting

2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) Pub Date : 2019-08-01 DOI:10.1109/MWSCAS.2019.8884858

Safaa A. Abdelfattah, A. Shrivastava, M. Onabajo

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Abstract

A symmetric chopper instrumentation amplifier architecture with two identical 8-bit digitally programmable capacitor banks and online digital calibration block are presented. Designed for long-term brain signal monitoring applications, the feedback capacitor banks generate negative capacitance to cancel the input capacitance from electrode cables to boost the input impedance to above 2 GΩ at 10 Hz. These banks are controlled by an automatic digital background calibration unit that includes an oscillation prevention scheme to ensure stable operation. A chopping technique is introduced to enhance the noise performance of the instrumentation amplifier in combination with the capacitive feedback loop that also contains chopping switches. The instrumentation amplifier and online calibration blocks are designed in 0.13-µm BiCMOS technology with a 1.2V supply, consuming 115.9 µW and 176 nW, respectively. Simulations show that the amplifier has a 26.9 dB gain, 8.06 KHz bandwidth, 0.52 µV input-referred noise integrated from 0.1-100Hz, and −49.9 dB THD with 1mV peak-to-peak input. The core layout area of the calibration block is 2100 µm2.

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一种具有全对称负电容产生反馈回路和输入阻抗升压在线数字校准的斩波仪表放大器

提出了一种对称斩波仪表放大器结构，该结构具有两个相同的8位数字可编程电容器组和在线数字校准块。为长期脑信号监测应用而设计，反馈电容器组产生负电容以抵消电极电缆的输入电容，从而在10 Hz时将输入阻抗提高到2 GΩ以上。这些银行由一个自动数字背景校准单元控制，该单元包括一个振荡预防方案，以确保稳定运行。采用斩波技术，结合包含斩波开关的电容反馈回路，提高了仪表放大器的噪声性能。仪器放大器和在线校准模块采用0.13µm BiCMOS技术设计，电源为1.2V，功耗分别为115.9µW和176 nW。仿真结果表明，该放大器的增益为26.9 dB，带宽为8.06 KHz, 0.1-100Hz范围内集成的输入参考噪声为0.52µV，峰值输入为1mV时的THD为- 49.9 dB。校准块的核心布局面积为2100µm2。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS)

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