ADC Comparator Offset Correction Without Signal Path Distortion
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Solution Overview
Problem
Existing analog-to-digital converters face issues with frequency characteristics deterioration and waveform distortion due to the addition of capacitance and resistance in the analog signal path, which impairs the reliability of A-D conversion, especially when offset correction is activated.
Innovation Solution
An analog-to-digital converter design that includes a track-and-hold circuit, a threshold voltage selection circuit, and a correction switching circuit, which allows for unified control of the input analog voltage to multiple comparators, reducing the need for individual switches and improving frequency characteristics by temporarily holding and delivering the analog voltage without additional switches, thereby minimizing waveform distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual switches are provided for each comparator to control input voltage, then offset correction can be performed, but frequency characteristics deteriorate and waveform distortion occurs
Solution Approach 1:
The patent merges the switch control function from individual comparators to a unified track-and-hold circuit. Instead of having separate switches for each comparator, a single track-and-hold circuit controls the input voltage for all comparators simultaneously, eliminating the harmful capacitance and resistance additions while maintaining offset correction capability through unified control.
Solution Approach 2:
The track-and-hold circuit acts as an intermediary between the input voltage source and the comparators. It temporarily holds the input voltage and distributes it to all comparators without requiring individual switches, thereby improving frequency characteristics while still enabling offset correction through its unified switching mechanism.
2Reliability
If individual switches are provided for each comparator, then offset correction is enabled, but device complexity increases
Solution Approach 1:
The patent reduces device complexity by merging multiple individual comparator switches into a single track-and-hold circuit. This unified structure eliminates the need for numerous separate switches while maintaining the ability to perform offset correction, thereby simplifying the overall device architecture.
Solution Approach 2:
The track-and-hold circuit serves multiple functions simultaneously: it acts as a unified switch for all comparators, provides temporary voltage holding, enables offset correction, and simplifies control logic. This multi-functionality reduces the overall device complexity compared to having individual switches for each comparator.
3Reliability
If individual switches are provided for each comparator, then offset correction can be performed, but control complexity increases
Solution Approach 1:
The patent simplifies control by merging individual comparator switch controls into a unified track-and-hold circuit control mechanism. A single control signal now manages the switching for all comparators, making the system easier to operate while retaining offset correction functionality through the unified control approach.
Data Source
AI summary
An analog-to-digital converter includes a track-and-hold circuit, a constant-voltage source, a threshold voltage selection circuit, a first comparator to a seventh comparator, an encoder, and a reference voltage output circuit. In a correction mode where the offsets of the first to seventh comparators are to be corrected, a track-and-hold circuit shuts off the input of an analog voltage to the first to seventh comparators by turning off the track-hold switch.