Design of CMOS Analog Front-End Local-Field Potential Chopper Amplifier with Stimulation Artifact Tolerance for Real-Time Closed-Loop Deep Brain Stimulation SoC Applications

Chung Yu Wu, Chi Wei Huang, Yu Wei Chen, Chin Kai Lai, Chung Chih Hung, Ming Dou Ker

Research output: Contribution to journalArticlepeer-review

Abstract

A CMOS analog front-end (AFE) local-field potential (LFP) chopper amplifier with stimulation artifact tolerance, improved right-leg driven (RLD) circuit, and improved auxiliary path is proposed. In the proposed CMOS AFE LFP chopper amplifier, common-mode artifact voltage (CMAV) and differential-mode artifact voltage (DMAV) removal using the analog template removal method are proposed to achieve good signal linearity during stimulation. An improved auxiliary path is employed to boost the input impedance and allow the negative stimulation artifact voltage passing through. The common-mode noise is suppressed by the improved RLD circuit. The chip is implemented in 0.18-μm CMOS technology and the total chip area is 5.46-mm2. With the improved auxiliary path, the measured input impedance is larger than 133 MΩ in the signal bandwidth and reaches 8.2 GΩ at DC. With the improved RLD circuit, the measured CMRR is 131 – 144 dB in the signal bandwidth. Under 60-μs pulse width and 130-Hz constant current stimulation (CCS) with ±1-V CMAV and ±50-mV DMAV, the measured THD at the SC Amp output of fabricated AFE LFP chopper amplifier is 1.28%. The measurement results of In vitro agar tests have shown that with ±1.6-mA CCS pulses injecting to agar, the measured THD is 1.69%. Experimental results of both electrical and agar tests have verified that the proposed AFE LFP chopper amplifier has good stimulation artifact tolerance.

Original languageEnglish
Pages (from-to)1-13
Number of pages13
JournalIEEE Transactions on Biomedical Circuits and Systems
DOIs
StateAccepted/In press - 2024

Keywords

  • Analog front-end (AFE) amplifier
  • Choppers (circuits)
  • Electrodes
  • Impedance
  • Real-time systems
  • Satellite broadcasting
  • Voltage
  • Voltage measurement
  • deep drain stimulation (DBS)
  • local-field potential (LFP)
  • rail-to-rail amplifier
  • stimulation artifact removal

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