Continuous-Time Sigma-Delta ADC Feedback Delay Stabilization
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Solution Overview
Problem
Sigma delta modulators face instability due to loop delay variations caused by manufacturing and temperature changes, affecting the performance of analog-to-digital converters.
Innovation Solution
A voltage-controlled delay element is integrated into the feedback loop of a continuous time sigma delta modulator to optimize and stabilize the delay, using a feedback loop controller and phase detector to adjust the delay based on input signals and stored delay data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a feedback loop is used to improve conversion accuracy, then measurement precision is improved, but loop delay causes instability
Solution Approach 1:
The patent measures the loop delay using a phase detector and stores the measurement in a register before using it to control the delay element. This preliminary measurement and storage allows the system to proactively compensate for delay variations, preventing instability while maintaining the feedback loop for accuracy improvement.
Solution Approach 2:
The patent uses a phase detector to continuously monitor the loop delay and feeds this information back to a delay controller, which adjusts the delay element accordingly. This feedback mechanism allows the system to dynamically compensate for delay variations, resolving the contradiction between using feedback for accuracy and avoiding feedback-induced instability.
2Reliability
If delay compensation is added to stabilize the feedback loop, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a phase detector as an intermediary component that measures the loop delay and converts it into a controllable signal. This intermediary simplifies the control task by providing a direct measurement of delay, making the overall compensation mechanism less complex despite adding the phase detector component.
Solution Approach 2:
The patent replaces complex mechanical or analog delay adjustment mechanisms with an electronically controlled delay element whose delay is precisely controlled by a voltage signal from the delay controller. This substitution simplifies the physical structure while achieving precise delay compensation for improved reliability.
3Manufacturing precision
If manufacturing variations are reduced to minimize delay variation, then manufacturing precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent enables the modulator to self-compensate for manufacturing variations by measuring its own loop delay using the phase detector and automatically adjusting the delay element through the delay controller. This self-service approach eliminates the need for expensive precision manufacturing processes, as the system adapts to its own characteristics after fabrication.
Solution Approach 2:
The patent changes the delay parameter dynamically by adjusting the control voltage to the delay element based on measured loop delay characteristics. This allows the system to compensate for manufacturing variations in delay without requiring precise manufacturing control, thereby reducing manufacturing complexity and cost.
Data Source
AI summary
A continuous time sigma delta analog to digital converter is provided. The continuous time sigma delta analog to digital converter may include, but is not limited to, an analog to digital converter having a feedback loop, and a feedback loop controller coupled to the analog to digital converter, the feedback loop controller configured to adjust delay in the feedback loop by controlling a variable delay component in the feedback loop.