ADC Channel Blending for High Dynamic Range Sample Error Reduction
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Solution Overview
Problem
High dynamic range digitization systems using multiple analog to digital converters face significant sample errors due to phase and amplitude errors between adjacent channels, leading to signal degradation and increased measurement errors in ultrasonic flaw detectors.
Innovation Solution
A method is introduced to proportionately blend the outputs of adjacent channels by calculating a blend factor based on the overflow conditions and output values of the converters, allowing for a smooth transition between channels and minimizing errors through digital logic circuits and blending processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple analog to digital converters are used to achieve higher dynamic range, then dynamic range is improved, but sample errors increase due to phase and amplitude errors between adjacent channels
Solution Approach 1:
The patent introduces a digital variable gain amplifier as an intermediary component between the analog to digital converters and the signal processing system. This digital VGA adjusts the gain of each converter channel individually in the digital domain, allowing precise control of amplitude relationships between channels without introducing the analog VGA problems. The digital intermediary enables accurate alignment of adjacent channels while maintaining the benefits of multiple converters for extended dynamic range.
Solution Approach 2:
The patent replaces the analog variable gain amplifier system with a digital variable gain amplifier system. By moving the gain control function from the analog domain to the digital domain, the system eliminates the need for analog filter components and DC offset compensation circuits. The digital implementation provides more reliable and precise control over channel amplitudes and phases, reducing sample errors while achieving the desired dynamic range extension.
2Measurement precision
If analog variable gain amplifiers are used to achieve higher dynamic range, then dynamic range is improved, but device complexity increases due to additional analog filter components and DC offset compensation
Solution Approach 1:
The patent substitutes the entire analog variable gain amplifier system with a digital variable gain amplifier system. This replacement eliminates the need for analog filter components, DC offset compensation circuits, and dynamic calibration mechanisms. The digital implementation achieves the same dynamic range extension function through software-based gain control, significantly reducing hardware complexity while improving reliability.
Solution Approach 2:
The patent extracts the variable gain function from the analog domain and relocates it to the digital domain. By taking out the analog VGA and its associated analog filter components and DC offset compensation requirements, the system retains the dynamic range extension capability while eliminating the complexity and reliability issues inherent in analog implementations.
3Measurement precision
If analog variable gain amplifiers are used to extend dynamic range, then dynamic range is improved, but ease of operation deteriorates due to difficult DC offset compensation and calibration requirements
Solution Approach 1:
The patent replaces the analog DC offset compensation mechanism with a digital solution. The digital variable gain amplifier operates on already-digitized signals, eliminating the need for dynamic DC offset adjustment during gain changes. This substitution makes the system much easier to operate, as the digital domain naturally handles offset issues without requiring manual calibration or complex compensation circuits.
Data Source
AI summary
A blending circuit is disclosed to be operable to combine plurality of digital outputs received from an analog to digital conversion system to create a composite digital signal. The analog to digital conversion system receives analog signals originated from multiple but substantially the same source signals, wherein the source signals being scaled to different degrees. A blending circuit deploys a blending factor to combine the digital outputs in a manner which blends and/or adjusts portion of each digital output being used to avoid over-flown portion of the digital outputs and to minimize phase and/or amplitude discontinuity of the composite digital signal.