Charge-Redistribution ADC Capacitor Switching for Dielectric Absorption
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Solution Overview
Problem
Dielectric absorption in capacitors leads to error charges in high-speed circuit arrangements, which are not well-characterized and can impact the accuracy of switched capacitor circuits, particularly in integrated circuits where this effect is often neglected but becomes significant in higher accuracy applications.
Innovation Solution
The approach involves splitting capacitors into smaller pieces and permutating them to cancel out memory effects, with a novel concept of swapping entire logical columns of capacitors instead of individual capacitors, reducing layout complexity and wiring effort, and enabling charge equalization to minimize common mode errors in differential signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If capacitors are used in high-speed circuit arrangements, then productivity is improved, but dielectric absorption leads to error charges that worsen measurement precision
Solution Approach 1:
The capacitor is divided into two separate capacitors (first capacitor and second capacitor) with different dielectric materials. This segmentation allows each capacitor to have complementary dielectric absorption characteristics, so that when one capacitor retains error charges, the other releases them, thereby canceling out the overall memory effect while maintaining high-speed operation.
Solution Approach 2:
The invention uses capacitors with different dielectric materials (first dielectric material and second dielectric material) that have different dielectric absorption characteristics. By combining these different materials in a composite capacitor structure, the system exploits their complementary properties to mitigate dielectric absorption errors while operating at high clock speeds.
2Measurement precision
If capacitors are split into smaller pieces to mitigate memory effects, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The capacitor is divided into two separate capacitors (first capacitor and second capacitor) with different dielectric materials. This segmentation allows each capacitor to have complementary dielectric absorption characteristics, so that when one capacitor retains error charges, the other releases them, thereby canceling out the overall memory effect while maintaining high-speed operation.
Solution Approach 2:
The first capacitor and second capacitor are combined in parallel within the same circuit structure, sharing common control signals and operational phases. This merging approach allows the complex segmented structure to operate as a unified component, reducing control complexity while maintaining the precision benefits of segmentation.
3Measurement precision
If individual capacitors are permutated to cancel memory effects, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The capacitor is divided into two separate capacitors (first capacitor and second capacitor) with different dielectric materials. This segmentation allows each capacitor to have complementary dielectric absorption characteristics, so that when one capacitor retains error charges, the other releases them, thereby canceling out the overall memory effect while maintaining high-speed operation.
Solution Approach 2:
Different regions of the capacitor structure use different dielectric materials with specific local properties optimized for their function. The first dielectric material and second dielectric material are selectively placed in different capacitors based on their complementary dielectric absorption characteristics, allowing each local region to contribute specifically to canceling memory effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively mitigates dielectric absorption errors by ensuring residual charges are equally distributed across polarity components, reducing common mode errors and enhancing the accuracy of differential output signals in sample-and-hold and analog-to-digital conversion circuits.
Implementation Method 1
Dielectric absorption, sometimes also called dielectric relaxation, is an effect that may occur in capacitors, and which may lead to error charges that remain within the capacitors
Data Source
Figure 1a~1b
Figure 1c
Figure 1d
AI summary
Examples relate to a circuit arrangement, a digital-to-analog conversion circuit, a charge-redistribution analog-to-digital conversion circuit and a method for controlling a circuit arrangement. The circuit arrangement comprises a plurality of charge stores. The plurality of charge stores is logically arranged in an array configuration comprising a plurality of logical columns of charge stores. The plurality of logical columns of charge stores comprise at least a first, a second, a third and a fourth column of charge stores. The circuit arrangement comprises a switching network operably coupled to the plurality of charge stores. The circuit arrangement comprises a control circuit configured to control the switching network. The control circuit is configured to affect a first circuit configuration in a first time segment and a second circuit configuration in a second time segment. The first circuit configuration and the second circuit configuration are different from one another. In the first circuit configuration the first and third columns of charge stores receive a first polarity component of a differential signal. In the first circuit configuration the second and fourth columns of charge stores receive a second polarity component of the differential signal. In the second circuit configuration the first and second columns of charge stores receive the first polarity component of the differential signal. In the second circuit configuration the third and fourth columns of charge stores receive the second polarity component of the differential signal.