A Low-Power, Auto-DC-Suppressed Photoplethysmography Readout System with Differential Current Mirrors and Wide Common-Mode Input Range Successive Approximation Register Analog-to-Digital Converter

Figures

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  Figure 1. Prior PPG readout system methodologies. (a) TIA with ADC, (b) LDC.

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  Figure 2. Proposed PPG readout system with DCM and input rail-to-rail SAR ADC.

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  Figure 3. Proposed PPG readout front-end circuits with differential current mirror (DCM).

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  Figure 4. Proposed wide common-mode input range SAR ADC with input rail-to-rail comparator.

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  Figure 5. Layout of proposed PPG readout systems.

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  Figure 6. Simulated results of transfer function for DCM in the proposed PPG readout system. (a) Transimpedance results in different input current conditions, (b) in Monte Carlo variations, (c) in different process corners, (d) in variable temperature ranges for different current conditions.

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  Figure 7. Simulated results of transient response for DCM in the proposed PPG readout system with different DC current situations.

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  Figure 8. Simulated FFT spectrum of the proposed WCMIR SAR ADC.

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  Figure 9. Compared SNDR at Vin = 0.8 Vpp between the conventional and proposed SAR ADC.