Delta-Sigma Modulator Filtering for Out-of-Band Noise Suppression
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Solution Overview
Problem
Conventional delta-sigma modulators face challenges in effectively reducing out-of-band quantization noise, which can adversely impact system performance due to the inherent trade-off between in-band and out-of-band frequency noise levels.
Innovation Solution
A delta-sigma modulator design that incorporates a second filter device to amplify specific frequencies in the out-of-band frequency range, either within a feedback loop or integrated with the first filter device, to suppress out-of-band quantization noise, utilizing resonators to target specific frequencies and enhance noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control loop is used to decrease quantization error in the in-band frequency range, then in-band noise is reduced, but out-of-band quantization noise increases
Solution Approach 1:
The patent applies the principle of converting harm into benefit by taking the harmful out-of-band quantization noise and using a second filter device to selectively amplify specific out-of-band frequencies. This amplification creates notches in the noise spectrum at those frequencies, effectively converting the harmful noise into a beneficial noise suppression mechanism. The quantization noise that would normally degrade system performance is instead used to create frequency-selective noise cancellation through the amplification-induced notches.
2Object-affected harmful factors
If a second filter device is added to suppress out-of-band quantization noise, then out-of-band noise is reduced, but device complexity increases
Solution Approach 1:
The patent applies the merging principle by integrating the second filter device with the existing first filter device or feedback loop infrastructure. Rather than adding a completely separate filtering system, the second filter device is combined with existing components, sharing common elements such as the feedback path and signal routing. This integration approach reduces the overall device complexity compared to implementing entirely independent filtering systems.
Solution Approach 2:
The second filter device is designed with multi-functionality, serving both as a noise suppression element and as part of the overall feedback control mechanism. The same filter structure that suppresses out-of-band quantization noise also contributes to the general signal processing function, thereby reducing the need for separate dedicated components and lowering overall system complexity.
3Object-affected harmful factors
If amplification of specific frequencies is applied in the control path, then quantization noise is suppressed at those frequencies, but power consumption increases
Solution Approach 1:
The patent applies the local quality principle by implementing frequency-selective amplification only at specific out-of-band frequencies where quantization noise suppression is most beneficial. Rather than applying broad-band amplification across the entire frequency spectrum, the second filter device is configured to amplify only the specific frequency components that require noise suppression. This localized approach minimizes unnecessary power consumption while achieving the desired noise reduction at critical frequencies.
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 approach allows for significant suppression of out-of-band quantization noise at specific frequencies, thereby improving system robustness and performance without compromising in-band noise reduction, as demonstrated by the amplification of frequencies within the control path leading to noise suppression in the closed loop.
Implementation Method 1
utilizing resonators to target specific frequencies and enhance noise suppression
Data Source
AI summary
A delta-sigma modulator which receives an input signal. The input signal is combined with a feedback signal and the combined signal is filtered by the delta-sigma modulator. The filtered signal is quantized, wherein the feedback signal is generated on the basis of the quantized signal. The quantized signal is output as an output signal. The input signal and/or the filtered signal and/or the feedback signal are filtered in such a way that at least one frequency in an out-of-band frequency range of the input signal is amplified in order to suppress out-of-band quantization noise at the at least one frequency.