Dual Quantizer Delta-Sigma Modulator With Feedback Noise Cancellation
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Solution Overview
Problem
The dual quantizer architecture for oversampling delta-sigma modulators introduces highly correlated quantization noise that degrades the spectral content, and existing solutions fail to effectively cancel this noise while reducing power consumption and area.
Innovation Solution
A modified dual quantizer architecture where the quantization noise of the second quantizer is cancelled by injecting its output into the feedback path, allowing the second quantizer to operate at a slower sampling rate than the first, and using a digital signal processing block to match the loop filter's signal transfer function, thereby reducing power consumption and area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a dual quantizer architecture is used for oversampling delta-sigma modulators, then power consumption and area can be reduced by running the second quantizer at a slower sampling rate, but the quantization noise of the second quantizer becomes highly correlated and significantly degrades the spectral content
Solution Approach 1:
The patent converts the harmful highly correlated quantization noise from the second quantizer into a useful signal by injecting it into the feedback path. This injected noise is then processed by the loop filter and combined with the first quantizer output, effectively canceling the degradation and improving spectral content while maintaining the low power consumption benefit of the slower second quantizer
Solution Approach 2:
The patent introduces a feedback mechanism where the output of the second quantizer is injected into the feedback path of the delta-sigma modulator. This feedback loop allows the system to compensate for the quantization noise by processing it through the loop filter and combining it appropriately, thereby resolving the spectral degradation issue while preserving the power consumption advantage
2Area of stationary object
If the second quantizer operates at a slower sampling rate, then power consumption and area are reduced, but the ability to effectively cancel quantization noise and maintain spectral integrity is compromised
Solution Approach 1:
The patent converts the harmful highly correlated quantization noise from the second quantizer into a useful signal by injecting it into the feedback path. This injected noise is then processed by the loop filter and combined with the first quantizer output, effectively canceling the degradation and improving spectral content while maintaining the low power consumption benefit of the slower second quantizer
Solution Approach 2:
The patent introduces an intermediary processing path where the second quantizer output is injected into the feedback path and processed by the loop filter. This intermediary mechanism allows the slower second quantizer to contribute usefully to the overall signal, maintaining spectral integrity despite the reduced sampling rate
Data Source
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AI summary
Power consumption of analog-to-digital converters (ADCs) is one important requirement for automotive and consumer devices. One flavor of an ADC is a dual quantizer architecture for oversampling delta-sigma modulators. The dual quantizer delta-sigma modulator has a first quantizer for digitizing the output of the loop filter and a second quantizer for digitizing the input of the quantizer. However, the quantization noise of the second quantizer is a highly correlated signal and significantly degrades the spectrum of the delta-sigma modulator. To address this issue, an improvement to the dual quantizer architecture is made to cancel the quantization noise of the second quantizer that is digitizing the input. Furthermore, the improvement allows the second quantizer to run at a much slower sampling rate than the first quantizer. Advantageously, the improvement provides reduction in power consumption and the overall area of modulator.