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Author: search.filters.author.Pawarangkoon, PrajuabSubject: search.filters.subject.Biopotential acquisition

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    A Nanopower EEG Low-Pass Filter Using Current-Sharing Vertical Differential Pairs
    (2025-01-01)
    Pawarangkoon, Prajuab
    ;
    Ahmad, Rafidah
    ;
    Abdullah Zawawi, Ruhaifi
    ;
    Abd Manaf, Asrulnizam
    ;
    Surakampontorn, Wanlop
    A follower-based g<inf>m</inf> - C low-pass filter that employs CMOS vertical source-couple-pair (VSCP) transconductors is proposed for practical use in EEG acquisition systems. The VSCP transconductor operates as a g<inf>m</inf> cell with current sharing and linearity enhancement features. It is applied in the first- and second-order g<inf>m</inf> - C sections cascaded to form a third-order low-pass filter targeting a 150-Hz bandwidth. To mitigate the effects of biasing current source mismatch, dynamic element matching (DEM) is optionally applied to the relevant biasing current source pairs, resulting in second harmonic distortion (HD2) and noise suppression. Implemented in a 0.18-µm process, the proposed filter consumes 16.3-nW power from a 1.2-V supply. Thanks to the DEM and VSCPs, the filter achieves a 150-mV<inf>P</inf> linear input range [measured at 1% total harmonic distortion (THD)], whereas the input-referred noise of 43 µV<inf>rms</inf> is obtained leading to a filter dynamic range (DR) of 65.15 dB. Overall performance comparisons with other recent nanopower filters indicate that the figure of merit (FoM) of this proposed filter is comparable, while the linear input range is larger.
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    A 38.4 nW, 1.2 V, 250-Hz, 2nd-Order gm - C LPF With Degenerative SCP Transconductors Achieving 800-mVPP Input Range and 82.1- μVrms IRN for ECG Acquisition
    (2025-01-01)
    Thanapitak, Surachoke
    ;
    Pawarangkoon, Prajuab
    ;
    Surakampontorn, Wanlop
    ;
    Ahmad, Rafidah
    ;
    Abdullah Zawawi, Ruhaifi
    In this brief, a 2{^{\text {nd} -order gm - C lowpass filter with a practical input linear range of 400mV P dedicated to ECG signal acquisition is proposed. This filter employs a degenerative source-coupled-pair circuit as a gm cell. It enhances the linear input range by a factor of × 4 compared with the source follower filter. Additionally, to mitigate the effect of current source mismatch, a dynamic element matching technique is applied. By doing so, HD2 is suppressed more than 1.5 dB over the entire passband frequency. This proposed filter is implemented in a 0.18 μ m CMOS process. It offers a 250-Hz bandwidth with input-referred noise and a dynamic range of 82.1 μ Vrms and 67.34 dB, respectively. The power consumption of 38.4 nW is achieved with a 1.2 V supply. Compared with other recent nano-power filters, the proposed filter provides the highest linear input range with competitive Figure-of-Merit to the top-tier designs. It is therefore beneficial to the practical implementation of a low-power ECG acquisition system.