Key result
A 0.35-mum CMOS front-end for PPG signal acquisition consumed 600 muW at 2.5 V, rejected DC photocurrent from 100 nA to 53.6 muA, and achieved cutoff frequencies of 0.46 and 2.8 Hz.
The proposed CMOS front-end provides robust DC photocurrent rejection and ultra-low cutoff frequencies for PPG signal acquisition while consuming minimal power.
Enables low-power wearable PPG monitoring; leaves open clinical validation before practice adoption.
A micro-power CMOS front-end, consisting of a transimpedance amplifier (TIA) and an ultralow cutoff frequency lowpass filter for the acquisition of photoplethysmographic signal (PPG) is presented. Robust DC photocurrent rejection for the pulsed signal source is achieved through a sample-and-hold stage in the feed-forward signal path and an error amplifier in the feedback path. Ultra-low cutoff frequency of the filter is achieved with a proposed technique that incorporates a pair of current-steering transistors that increases the effective filter capacitance. The design was realized in a 0.35-mum CMOS technology. It consumes 600 muW at 2.5 V, rejects DC photocurrent ranged from 100 nA to 53.6 muA, and achieves lower-band and upper-band - 3-dB cutoff frequencies of 0.46 and 2.8 Hz, respectively.
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Wong et al. (2008) studied this question. micro-power CMOS front-end was evaluated on DC photocurrent rejection and cutoff frequencies. A 0.35-mum CMOS front-end for PPG signal acquisition consumed 600 muW at 2.5 V, rejected DC photocurrent from 100 nA to 53.6 muA, and achieved cutoff frequencies of 0.46 and 2.8 Hz.
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