Hybrid Analog Digital Feedback Control for Sensor Precision
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Solution Overview
Problem
Existing closed-loop sensing systems face challenges in achieving high bandwidth, high dynamic range, and high precision due to limitations in analog feedback loops, such as offset voltages and demodulator imperfections, while digital feedback loops offer high precision but lower dynamic range, and high-resolution digital-to-analog converters are limited by lower bandwidth.
Innovation Solution
The method involves demodulating sense signals using both analog and digital demodulators, determining the difference between their outputs, and integrating it to generate a feedback control signal, utilizing high-resolution digital converters to correct analog errors, and employing techniques like dithering with random noise to enhance resolution without impacting bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog feedback loops are used, then high bandwidth and dynamic range are achieved, but precision is limited due to analog errors
Solution Approach 1:
The patent combines analog and digital feedback loops into a hybrid system where the analog loop handles high-bandwidth signals and the digital loop corrects precision errors. The analog demodulator processes the sense signal at high speed while the digital demodulator accumulates and corrects precision errors, merging the strengths of both approaches to achieve high precision without sacrificing bandwidth.
Solution Approach 2:
The patent introduces an intermediary error correction mechanism where the digital loop acts as a mediator to correct analog errors. The digital accumulator calculates the difference between analog and digital demodulator outputs, and this correction signal is fed back to compensate for analog errors, effectively using the digital system as an intermediary to improve overall precision.
2Measurement precision
If digital feedback loops with digital demodulators are used, then high precision is achieved, but dynamic range is reduced
Solution Approach 1:
The patent segments the feedback loop into two functional parts: an analog segment that handles the full dynamic range at high bandwidth, and a digital segment that focuses on precision correction. The analog demodulator processes the complete signal range while the digital accumulator only processes the precision correction component, allowing each segment to optimize for its specific function without compromising the other.
3Measurement precision
If high resolution digital to analog converters are used, then precision is improved, but bandwidth is reduced
Solution Approach 1:
The patent applies partial action by using a lower-resolution DAC (16-bit) for the high-bandwidth analog feedback path, which is sufficient for the dynamic range requirements. The excessive precision requirements are met separately by the digital accumulator that calculates correction values with higher precision. This partial application of high resolution only where needed maintains bandwidth while achieving the required precision.
Data Source
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AI summary
Improved methods and systems for feedback signals in a sensor system. An example method demodulates a sense signal using an analog demodulator (60) and also demodulates the sense signal using a digital demodulator (64). The difference between the result of the analog demodulator and the digital demodulator is determined (50) and then integrated (52). A sensor feedback control signal is generated (54) based on the integrated difference.