MASH ADC Noise Coupling for High SNR Without High-Order Loops
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Solution Overview
Problem
Existing analog-to-digital converters face challenges in achieving high signal-to-noise ratio (SNR) without increasing power consumption or using high-order loop filters, which can compromise stability and maximum stable amplitude.
Innovation Solution
The converter employs a multi-stage noise shaping (MASH) structure, a digital noise coupling filter, and a digital filter to improve SNR by reducing quantization errors, thereby maintaining stability and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling rate is increased to improve signal-to-noise ratio, then the signal-to-noise ratio is improved, but the power consumption of the converter increases
Solution Approach 1:
The patent replaces the conventional analog noise filtering approach with a digital noise shaping and filtering system. By using digital signal processing techniques (noise shaping filter and digital filter) instead of increasing analog sampling rate, the system achieves improved signal-to-noise ratio without the associated increase in power consumption that would result from higher sampling rates
Solution Approach 2:
The patent extracts and processes quantization noise separately from the signal. By generating a quantization noise signal and processing it through the noise shaping filter and digital filter, the system removes noise components from the output signal path, achieving improved signal-to-noise ratio without needing to increase the main sampling rate
2Measurement precision
If a high-order loop filter is used to obtain high resolution, then the resolution is improved, but the stability of the circuit is weakened and maximum stable amplitude is reduced
Solution Approach 1:
The patent substitutes the high-order analog loop filter with a digital filtering system. By using digital noise shaping and digital filtering techniques, the system achieves high resolution without requiring high-order analog filters that would compromise circuit stability and reduce maximum stable amplitude
Solution Approach 2:
The patent introduces a quantization noise signal as an intermediary element. This noise signal is processed through the noise shaping filter and digital filter to achieve noise reduction and high resolution without needing high-order loop filters, thereby maintaining circuit stability
Data Source
AI summary
An example converter includes a first adder, a first analog-to-digital converter, a second analog-to-digital converter, a digital noise coupling filter, and a digital filter. The first adder is configured to generate a differential analog signal corresponding to a difference between a first analog signal and a second analog signal. The first analog-to-digital converter is configured to convert the differential analog signal to a first digital signal. The second analog-to-digital converter is configured to convert a first quantization error corresponding to a difference between the differential analog signal and the first digital signal to a second digital signal. The digital noise coupling filter is configured to generate a second digital quantization signal corresponding to the second analog signal. The digital filter is configured to generate an output signal based on the first digital signal and the second digital signal.