PPG Circuit Partial Sampling for Low-Power Biometric Detection
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Solution Overview
Problem
Biological characteristics detection devices face issues with accuracy due to improper positioning of phototransducers and displacement during measurements, leading to increased power consumption and instability in current-to-voltage converters.
Innovation Solution
A PPG circuit with multiple receiving channels and a controller that operates in partial and full sampling phases to selectively activate photoelectric converters, reducing power consumption and improving accuracy by minimizing unnecessary light source activation and parallel connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple photoelectric converters are activated simultaneously to improve measurement accuracy and compensate for positioning errors, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The system activates only J receiving channels (where J < K) during the partial sampling phase instead of all K channels, performing partial sampling to reduce power consumption while still obtaining sufficient measurement data. This partial action resolves the contradiction by using fewer photoelectric converters than the total available, thereby reducing energy consumption while maintaining acceptable measurement accuracy.
Solution Approach 2:
The system implements periodic switching between partial sampling phase and full sampling phase. During normal operation, only J channels are activated (partial sampling), but periodically the system switches to full sampling with all K channels to re-select optimal receiving channels. This periodic full sampling ensures measurement accuracy is maintained while most of the time the system operates in low-power partial sampling mode.
2Reliability
If all receiving channels are activated to ensure sufficient sampling data, then measurement reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
The system performs partial sampling by activating only J receiving channels (where J < K) during normal operation, reducing the complexity of the active circuit while maintaining measurement reliability through the periodic full sampling phase that ensures sufficient data for reliable channel selection.
Solution Approach 2:
The system dynamically switches between partial sampling mode (J channels active) and full sampling mode (all K channels active). The controller adapts the number of active receiving channels based on the operational phase, making the system configuration dynamic rather than static. This dynamic approach allows the system to balance reliability and complexity by using fewer channels most of the time while periodically utilizing all channels for optimal channel selection.
3Productivity
If multiple photoelectric converters are connected in parallel to increase sampling capacity, then productivity is improved, but parasitic capacitance effects increase causing instability
Solution Approach 1:
The system connects all K photoelectric converters in parallel to maintain high sampling capacity and productivity, but during normal operation only J channels (whereJ < K) are activated for sampling. This partial activation approach allows the system to have the capability of all K channels available while actually using fewer at any given time, thereby reducing parasitic capacitance effects and improving current-to-voltage converter stability while maintaining high sampling capacity when needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces power consumption and enhances accuracy by optimizing the sampling process, while maintaining measurement stability and reducing parasitic capacitance effects.
Implementation Method 1
N photoelectric converters are divided into K sets of photoelectric converter sets, the K receiving channels respectively correspond to the K sets of photoelectric converter sets
Data Source
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AI summary
The present application discloses a PPG circuit (103), a biological characteristics detection device and a biological characteristics detection method. The PPG circuit is configured to control a light source and N photoelectric converters to sense biological characteristics of an object under test (101); the PPG circuit includes: a transmitting channel (102), K receiving channels (104_1- 104 K), wherein the N photoelectric converters are divided into K sets of photoelectric converter sets, and the K receiving channels respectively correspond to K sets of photoelectric converter sets; and a controller (106), configured to control the PPG circuit to operate in a partial sampling phase or an full sampling phase, so as to generates J or K biological characteristics sampling results (DR) during each of the pulse repetition cycles.