Counter Circuit Digital Gain Bypass for ADC Linear Output
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Solution Overview
Problem
Conventional image sensors require post-processing to achieve linear output in multi-resolution analog-to-digital converters (ADCs), which necessitates detailed knowledge of the conversion curve, and the digital gain and ramp signal correlation is not transparent to back-end processing.
Innovation Solution
The implementation of counter circuits for ADCs that can apply digital gain by bypassing counter stages, allowing for linear output data and correlating digital gain with a ramp signal, enabling multi-resolution conversion transparent to back-end processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional ADC conversion is used, then the conversion process is simple, but post-processing is required to achieve linear output which increases device complexity
Solution Approach 1:
The patent applies preliminary action by pre-correlating the digital gain with the ramp signal during the ADC conversion process itself, rather than requiring post-processing correction. The counter circuit is designed to automatically apply the appropriate digital gain based on the ramp signal slope, so that linear output is achieved directly from the conversion process without requiring subsequent post-processing operations.
2Productivity
If digital gain is applied in conventional ADCs, then conversion speed may be improved, but the digital gain and ramp signal correlation is not transparent to back-end processing
Solution Approach 1:
The patent implements feedback by making the counter circuit aware of the ramp signal characteristics. The digital gain application is controlled based on feedback from the ramp signal slope, ensuring that the gain applied is directly correlated with the ramp signal. This feedback mechanism ensures that back-end processing receives transparent, correctly scaled digital values without loss of information about the conversion relationship.
3Measurement precision
If multi-resolution conversion is implemented, then conversion precision is improved, but detailed knowledge of the conversion curve is required which increases device complexity
Solution Approach 1:
The patent applies segmentation by dividing the ADC conversion process into multiple resolution stages with different ramp signal slopes. The counter circuit is segmented to handle different gain requirements at different conversion stages. This segmentation allows multi-resolution conversion to be achieved through structured, modular counter stages rather than requiring complex overall conversion curve knowledge, simplifying the device architecture.
Data Source
AI summary
A counter circuit for an analog to digital converter includes: a plurality of counter stages configured to obtain an integer multiple of a digital gain for the analog to digital converter by bypassing at least one of the plurality of counter stages. An analog-to-digital converter includes at least one counter circuit, and an image sensor includes the analog-to-digital converter, which includes the counter circuit.