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A Low-power Low-noise Multi-Channel Biopotential Measurement IC with Motion Artifact Suppression Capability

Mohammadi, Ehsan | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53277 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fotowat-Ahmadi, Ali
  7. Abstract:
  8. Long-term Multi-Channel Bio-Signal monitoring in a comfort way is demanding for emerging applications in everyday life. Typically, in multi-channel amplification, one amplifier per channel is employed. However, the bio-signal amplification requires lower bandwidth in comparison with the available speed of CMOS amplifiers. Therefore, it is sensible to develop a practical circuit trading the excess CMOS bandwidth with power consumption. The proposed circuit, which has three inputs, performs amplification through three stages; First, the inputs are applied to a 3 to 1 time-domain multiplexer. Second, a Current Feedback Instrumentation Amplifier (CFIA) is utilized. Finally, the amplified signal will be split into three channels by a de-multiplexer so that the three inputs are amplified by only one amplifier. Thus, power consumption is reduced by a factor of 3. To mitigate low-frequency op-amp imperfections, such as flicker noise and offset, a chopping process is required at the input and output of the amplifier. The proposed method merges the chopper into multiplexer and demultiplexer. Besides, I take advantage of the electrode-tissue impedance measurement method to suppress motion artifact. I accomplished the circuit design, layout, and post-layout simulation. The proposed circuit is fabricated in 0.18-micron CMOS. The current consumption of the circuit is 2uA, in case both amplification chain and current generator circuits are activated. In this mode, the 3 bio signal channels as well as the 3 electrode-tissue impedance signals are amplified. Gain matching between channels, CMRR, and input impedance are more than 62dB, 92dB, and 500MΩ, respectively. The power spectral density of input referred noise is 110nV/sqrt(Hz). The occupied per channel is 0.028mm2
  9. Keywords:
  10. Motion Artifacts ; Noise Removing ; Instrumentation Amplifier (IA) ; Multi-Channel Amplifier ; Electrode-Tissue Impedance ; Multi-Channel Bio-Signals Monitoring

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