Analog Residue Quantizer for High Dynamic Range Image A/D Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensors face challenges in achieving high dynamic range and efficient analog-to-digital conversion, particularly in CMOS devices, where noise and signal deterioration occur due to the need for off-chip processing and increased complexity with multiple ADCs.
Innovation Solution
A signal processor with a quantizer that retains the analog residue of an analog signal for further processing, allowing for increased accuracy in A/D conversion and enabling high dynamic range imaging by integrating the signal within each pixel, reducing noise and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple ADCs are provided to increase A/D conversion speed, then conversion speed is improved, but circuit complexity and footprint increase
Solution Approach 1:
The patent divides the A/D conversion process into multiple stages: a first quantizer performs initial quantization and outputs a first digital value, while a second quantizer processes the analog residue to output a second digital value. This segmentation allows the system to achieve high conversion speed through parallel processing without requiring multiple complete ADC circuits, thereby reducing overall circuit complexity while maintaining fast conversion performance.
2Adaptability or versatility
If A/D conversion is performed off-chip for CCD image sensors, then compatibility with CCD technology is achieved, but signal transmission distance increases causing noise and deterioration
Solution Approach 1:
The patent introduces an on-chip analog residue processing path that acts as an intermediary between the photodetector array and off-chip A/D conversion. The analog residue from the first quantizer is processed by a second quantizer before being combined with the first digital value, enabling partial on-chip processing that reduces signal transmission distance and minimizes noise while maintaining compatibility with off-chip conversion architectures.
3Ease of manufacture
If conventional CMOS ADCs are used with CCD image sensors, then semiconductor processing compatibility is achieved, but additional processing complexity is required
Solution Approach 1:
The patent implements a multi-functional quantizer architecture where the first quantizer performs initial A/D conversion and the second quantizer processes the analog residue. This universal architecture can handle both CCD and CMOS sensor outputs, providing compatibility across different sensor technologies while managing processing complexity through a standardized two-stage approach that leverages conventional CMOS ADC capabilities.
Data Source
AI summary
In one or more embodiments, an apparatus and method for processing an analog signal into a digital signal includes a quantizer that converts the analog signal, which can have any value within a given range of values, into a fixed set of discrete values. An analog residue, i.e. the quantization error caused by the difference between the analog value of the integrated analog signal and the closest corresponding discrete quantized value, is outputted. The analog residue can be further processed to increase the accuracy of the A/D conversion. Multiple quantizer stages can be provided to perform A/D conversion of the analog signal over multiple integration periods, e.g. in multi-shot and time-delay integration applications. The analog signal may represent an image signal.