Sensor Pixel Circuit Periodic Biasing for Noise Reduction
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Solution Overview
Problem
Existing sensor pixel systems face challenges in reducing flicker noise and transistor aging, which affect the sensitivity and reliability of imaging applications, particularly in biomedical and bio-molecular imaging.
Innovation Solution
The proposed solution involves a sensor pixel circuit with amplifying and switch transistors, a storage capacitor, and a sensor, where the transistors are biased using a unique timing scheme that alternates bias lines during readout cycles to reduce noise and minimize transistor stress, incorporating a variable capacitor for improved sensitivity and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous biasing is used to maintain transistor operation, then sensitivity is improved, but transistor aging increases and reliability deteriorates
Solution Approach 1:
The patent implements periodic biasing where transistors are alternately activated and deactivated in cycles. During active periods, transistors perform sensing and amplification; during inactive periods, they rest to reduce aging. This periodic operation maintains sensitivity while extending transistor lifespan by preventing continuous stress.
2Measurement precision
If continuous operation is used to maintain signal amplification, then sensitivity is improved, but flicker noise increases
Solution Approach 1:
The patent uses periodic biasing cycles that alternately activate and deactivate transistors. By interrupting continuous operation with rest periods, the patent reduces flicker noise (1/f noise) generation while maintaining signal amplification capability during active phases. The timing is optimized to balance amplification quality with noise reduction.
3Measurement precision
If continuous biasing is applied to maintain transistor performance, then sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic biasing where transistors are activated only during necessary sensing and readout operations, then deactivated to reduce power consumption. This approach maintains sensitivity during active periods while significantly reducing average power consumption compared to continuous biasing, making the sensor suitable for low-power applications.
Data Source
AI summary
One sensor pixel includes amplifying transistor, coupled between first bias line and data line; switch transistor, operated by control line and coupled between data line and gate of amplifying transistor; storage capacitor, coupled to second bias line; and sensor being coupled to gate of amplifying transistor. Another sensor pixel includes first amplifying transistor coupled between first bias line and data line; second amplifying transistor being coupled between second bias line and data line; switch transistor being operated by control line and being coupled between data line and gates of first and second amplifying transistors; storage capacitor coupled to gates of first and second amplifying transistors; and sensor coupled to gates of first and second amplifying transistors. Trap-assisted absorption, variable capacitor described for sensor pixels, and also biasing to reduce flicker and aging, and to compensate for aging, described for sensor pixels.