Sensor Circuit Noise Elimination via Signal Segmentation
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Solution Overview
Problem
Current sensing circuits using correlated double sampling can only effectively remove non-environmental noise, failing to eliminate both offset values caused by pixel defects during fabrication and environmental noise simultaneously.
Innovation Solution
A sensor circuit with a reference circuit and comparison circuit is designed, utilizing fully covered and uncovered pixel structures to generate and compare sensing signals, allowing for the elimination of sensing offsets and errors by recording a count signal when the ramp and second sensing signals are equal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If correlated double sampling is used to eliminate offset values, then manufacturing precision is improved, but environmental noise cannot be eliminated
Solution Approach 1:
The sensing signals are segmented into multiple components: offset values from pixel defects and environmental noise. By using fully covered and uncovered pixel structures, the offset values are separated and eliminated through subtraction, while environmental noise is captured and removed through averaging multiple first sensing signals. This segmentation allows independent elimination of each noise component.
Solution Approach 2:
Environmental noise is measured and stored in advance through multiple first sensing signals obtained from fully covered pixel structures before the actual sensing process. This preliminary measurement of environmental noise allows it to be subtracted from the second sensing signal, eliminating its harmful effects on the final measurement.
2Manufacturing precision
If sensing values are subtracted at different times, then offset values are eliminated, but environmental noise varies and cannot be perfectly removed
Solution Approach 1:
Multiple first sensing signals obtained at different times are merged through averaging to produce a stable representation of environmental noise. This combined environmental noise value is then subtracted from the second sensing signal, allowing effective removal of environmental noise while maintaining offset elimination through the subtraction of fully covered and uncovered pixel structures.
3Measurement precision
If multiple sensing operations are performed, then noise elimination capability is improved, but device complexity increases
Solution Approach 1:
The fully covered pixel structures serve multiple functions: they generate first sensing signals for environmental noise measurement and also provide offset value information through comparison with uncovered pixels. This multi-functionality reduces the need for separate dedicated noise reference circuits, thereby limiting the increase in device complexity while maintaining improved noise elimination capability.
Data Source
AI summary
The present invention provides a sensor circuit with noise elimination comprising: a reference circuit which receives plural first sensing signals and generates a ramp signal based on the first sensing signal; and a comparison circuit which is coupled to the reference circuit, and which receives a second sensing signal and a ramp signal and generates a count signal based on the ramp signal and the second sensing signal and records the count signal at the time when the ramp signal is equal to the second sensing signal, thereby eliminating the noise of the second sensing signal to obtain a noise-free sensing value. The count signal is recorded when the ramp signal and the second sense signal are equal, so that the noise of the second sense signal is eliminated and a noise-free sense value is obtained.