Audio Delta-Sigma Modulator Resonator for Stable Noise Shaping
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Solution Overview
Problem
High-order delta sigma modulators are unstable and impractical for achieving precise noise transfer function shaping, which is essential for providing a high signal-to-noise ratio, especially in audio applications where noise interference can be detrimental.
Innovation Solution
A system comprising a preamplifier and a resonator that adjusts the amplitude of an analog signal and noise transfer function, coupled with a feedback loop and integrators in a feedforward topology, to provide greater attenuation to noise in specific frequency bands, thereby stabilizing the circuit and enhancing noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-order delta sigma modulators are used to achieve precise noise transfer function shaping, then signal-to-noise ratio is improved, but circuit stability deteriorates
Solution Approach 1:
The patent divides the high-order modulator into a cascaded structure of multiple lower-order modulators (typically two second-order modulators). Each stage processes the signal independently with its own integrators and quantizers, allowing precise noise transfer function shaping through the cumulative effect of multiple stages while maintaining the stability of individual lower-order sections. This segmentation enables achieving high-order noise shaping performance without the instability of a single high-order circuit.
2Measurement precision
If high-order circuits are used to achieve greater noise attenuation, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
By segmenting the high-order noise attenuation function into multiple lower-order stages, the patent reduces the complexity of each individual circuit block while achieving the cumulative noise attenuation effect of a high-order system. Each second-order modulator stage uses a manageable number of integrators and feedback paths, making the overall system more implementable and less complex than a single high-order design.
Solution Approach 2:
The patent combines multiple lower-order modulator stages in a cascaded configuration where the output of one stage becomes the input to the next. This merging of simpler blocks achieves the equivalent noise attenuation performance of a high-order modulator while maintaining the practical advantages of modular, lower-order circuit design throughout the system.
3Measurement precision
If high-order modulators are used to achieve precise noise shaping, then signal-to-noise ratio is improved, but power consumption increases
Solution Approach 1:
The patent segments the power consumption across multiple lower-order stages, where each stage operates at lower power levels compared to a single high-order modulator. The distributed architecture allows for better power management and reduces the peak power requirements, while the cumulative noise shaping precision of all stages together achieves the desired signal-to-noise ratio improvement.
Data Source
AI summary
There is a presented a system for setting a noise transfer function comprising an input configured to receive an analog signal; a quantizer configured to quantize the analog signal to produce a digital signal; a preamplifier configured to adjust at least the amplitude the analog signal; and a resonator configured to adjust at least the amplitude of the analog signal, an output of the resonator being coupled to an output of the preamplifier, the system providing greater attenuation to the analog signal in a frequency band determined by the preamplifier and the resonator.