Delta-Sigma Modulator Digital Loop-Delay Compensation
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Solution Overview
Problem
Conventional delta-sigma modulators face excess-loop delay issues due to loop delay, which is inadequately addressed by analog compensation paths that increase power consumption and distortion.
Innovation Solution
A digitally-assisted compensation filter is introduced in a continuous-time delta-sigma modulator, using a digital-to-analog converter to feed output back to the integration circuit, effectively compensating for loop delay without additional analog circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an analog compensation path is added to resolve loop delay, then the modulator system pole shift is corrected, but power consumption increases and distortion increases
Solution Approach 1:
The patent replaces the analog compensation path with a digital compensation filter implemented in the feedback loop. The digital filter uses delay elements and adders to compensate for excess loop delay, substituting digital signal processing for analog circuitry. This eliminates the need for additional analog compensation components while maintaining modulator stability and reducing power consumption.
Solution Approach 2:
The patent modifies the feedback DAC coefficients to account for the digital compensation filter's delay characteristics. By adjusting these parameters, the system achieves proper pole placement and noise transfer function characteristics without requiring additional analog compensation paths, thereby reducing power consumption while maintaining reliability.
2Reliability
If an analog compensation path is added to resolve loop delay, then the modulator system pole shift is corrected, but distortion increases
Solution Approach 1:
The patent substitutes digital compensation filter circuitry for analog compensation paths. The digital implementation using delay elements and adders introduces no additional analog distortion, whereas analog compensation paths add distortion due to their inherent analog circuit characteristics. This substitution maintains system stability while eliminating the distortion penalty.
3Use of energy by moving object
If a digital compensation filter is used instead of analog compensation path, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The patent segments the compensation function into discrete digital components within the feedback loop - delay elements, adders, and modified DAC coefficient generation. This segmentation allows the compensation function to be implemented using standard digital logic building blocks, reducing overall complexity compared to designing complex analog compensation circuits while maintaining power efficiency.
4Object-generated harmful factors
If a digital compensation filter is used instead of analog compensation path, then distortion is reduced, but device complexity increases
Solution Approach 1:
The patent replaces analog compensation circuitry with digital signal processing elements. The digital implementation inherently produces less distortion than analog circuits while achieving the same pole correction function. The complexity increase is offset by the elimination of precision analog components and the use of robust digital logic that is easier to manufacture with consistent performance.
Data Source
AI summary
A modulator is constructed with a loop-delay compensation. A delta-sigma modulator generates a quantization code, and a digital compensation filter receives the quantization code and outputs a digital code. The digital compensation filter then feeds the digital code back to the delta-sigma modulator.