Programmable ADC Quantization for Wide Dynamic Range Imaging
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Solution Overview
Problem
Analog-to-digital converters (ADCs) in image processing face challenges in reducing quantization error and achieving a wide dynamic range, as fixed quantization schemes can degrade performance across varying light intensities and environments, leading to non-uniform quantization errors that affect image fidelity.
Innovation Solution
An ADC with programmable quantization resolutions, allowing for adaptive quantization schemes based on ambient light intensity and specific pixel cell conditions, where different quantization resolutions are applied to different sub-ranges of light intensities, optimizing quantization error reduction and dynamic range extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed quantization scheme is used, then the ADC structure is simple, but quantization error increases and dynamic range is limited
Solution Approach 1:
The patent implements a dynamic quantization scheme where the quantization resolution is adjusted based on the input signal characteristics. The system switches between different quantization modes (first quantization mode for low signal levels, second quantization mode for high signal levels) to optimize measurement precision across the dynamic range, resolving the contradiction between fixed simplicity and adaptive precision.
Solution Approach 2:
The patent changes the quantization parameter (resolution) dynamically based on the input signal amplitude. By modifying the quantization step size according to signal level, the system achieves high precision for both weak and strong signals without requiring a uniformly high-resolution converter, thus improving measurement precision while controlling device complexity.
2Measurement precision
If high quantization resolution is applied uniformly, then quantization error is reduced, but power consumption increases and dynamic range is compromised
Solution Approach 1:
The patent applies different quantization resolutions to different signal level ranges rather than using a uniform high resolution across the entire dynamic range. Weak signals (below threshold) use a first quantization mode with higher effective precision, while strong signals (above threshold) use a second quantization mode, optimizing the balance between quantization error reduction and power consumption for each local signal condition.
Solution Approach 2:
The system applies high quantization resolution only when necessary (for weak signals below the threshold) rather than uniformly across all signal levels. This partial application of high resolution reduces overall power consumption while maintaining measurement precision where it is most needed, resolving the contradiction between error reduction and energy efficiency.
3Ease of operation
If a single quantization mode is used, then the ADC is easy to operate, but performance degrades across varying light intensities
Solution Approach 1:
The patent implements automatic switching between two quantization modes based on the input signal amplitude relative to a threshold. The system dynamically adapts its operation: using the first quantization mode for signals below the threshold and the second mode for signals above the threshold, maintaining optimal performance across varying light intensities while preserving ease of operation through automated control.
Solution Approach 2:
The ADC is designed to perform multiple quantization functions within a single device structure. It can operate in either the first quantization mode or the second quantization mode depending on the input signal characteristics, providing universal adaptability to different light intensity conditions while maintaining a unified operational interface that preserves ease of use.
Data Source
AI summary
Methods and systems for performing analog-to-digital conversion are proposed. In one example, An analog-to-digital converter (ADC) comprising a quantizer, the quantizer having a first quantization resolution for a first quantization operation subrange and a second quantization resolution for a second quantization operation subrange. At least one of the first quantization resolution or the first quantization operation subrange is programmable. At least one of the second quantization resolution or the second quantization operation subrange is programmable. The quantizer is configured to: receive an input voltage; and based on whether the input voltage belongs to the first quantization operation subrange or to the second quantization operation subrange, quantize the input voltage at the first quantization resolution or at the second quantization resolution to generate a digital output.