Sigma-Delta Quantizer With Passive Error Feedback Noise Shaping
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Solution Overview
Problem
Conventional sigma-delta modulators face challenges in achieving high-order noise shaping while maintaining low power consumption and system stability, as the number of analog integrators increases, leading to deteriorating loop stability and higher power consumption.
Innovation Solution
A quantizer for a sigma-delta modulator is designed with an integrator, integrating capacitors, and passive low-pass filters that feed back filtered quantization error signals to achieve second-order noise shaping, reducing power consumption by using passive components that do not consume additional energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plurality of analog integrators are cascaded to achieve high-order noise shaping, then noise shaping capability is improved, but power consumption increases and loop stability deteriorates
Solution Approach 1:
The patent replaces active analog integrators with a passive low-pass filter structure to achieve noise shaping. Instead of using multiple energy-consuming analog integrators, the invention uses a passive filter with capacitors and resistors that shapes the quantization noise spectrum without requiring additional active power consumption, thereby resolving the contradiction between noise shaping capability and power consumption
Solution Approach 2:
The patent introduces a passive low-pass filter as an intermediary component between the quantizer and the feedback path. This filter mediates the noise shaping function, allowing the system to achieve high-order noise shaping through its transfer function characteristics rather than through multiple active integrators, thus reducing power consumption while maintaining noise shaping performance
2Measurement precision
If a plurality of analog integrators are cascaded to achieve high-order noise shaping, then noise shaping capability is improved, but loop stability deteriorates
Solution Approach 1:
The patent substitutes active analog integrators with a passive low-pass filter structure that inherently provides stability. The passive filter's transfer function achieves the desired noise shaping effect without introducing the stability issues associated with multiple cascaded active integrators, as passive components do not add phase shifts that could cause oscillation
Solution Approach 2:
The patent utilizes feedback through the passive low-pass filter to achieve noise shaping. The filter is positioned in the feedback path of the sigma-delta modulator, allowing it to shape the quantization noise while the feedback mechanism maintains loop stability by continuously adjusting the signal based on the filtered error signal
3Use of energy by moving object
If passive low-pass filters are used for noise shaping, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The passive low-pass filter structure serves multiple functions simultaneously: it acts as a noise shaping element, a frequency selective filter, and a feedback path component. By making this single passive structure multi-functional, the patent avoids the need for separate active integrators and filters, thereby reducing overall device complexity while maintaining low power consumption
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
The solution enables effective second-order noise shaping without significant power consumption increases, improving noise shaping capabilities while maintaining system stability and reducing power consumption.
Implementation Method 1
an integrating capacitor configured to store the quantization error signal for the Kth period, so as to weight the internal signal in a (K+1)th sampling period
Implementation Method 2
a passive low-pass filter configured to acquire the quantization error signal for the Kth period in a Kth discharge period, generate a filtered quantization error signal according to the quantization error signal
Data Source
AI summary
A quantizer for a sigma-delta modulator, a sigma-delta modulator, and a method of shaping noise are provided. The quantizer includes: an integrator configured to generate, in a Kth sampling period, a quantization error signal for a Kth period according to an internal signal, a quantization error signal for a (K−1)th period, a filtered quantization error signal for the (K−1)th period and a filtered quantization error signal for a (K−2)th period; an integrating capacitor configured to store the quantization error signal for the Kth period, to weight the internal signal in a (K+1)th sampling period; a passive low-pass filter configured to acquire the quantization error signal for the Kth period in a Kth discharge period, and feed back the filtered quantization error signal to the integrator in a (K+1)th sampling period and a (K+2)th sampling period; and a comparator configured to quantize the quantization error signal for the Kth period.