Sampling Quantization Converter with Multi-Channel Noise Shaping
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Solution Overview
Problem
Conventional analog-to-digital converters (ADCs) face limitations in achieving high instantaneous bandwidth and resolution, particularly at very high sample rates, due to issues such as quantization noise, clock jitter, and thermal noise, which restrict their performance beyond the Nyquist limit.
Innovation Solution
The implementation of a Multi-Channel Bandpass Oversampling (MBO) technique, which employs continuous-time Diplexed Feedback Loops (DFLs) for quantization noise shaping and Moving Average Reconstruction (MAR) filters for signal reconstruction, allowing for improved noise shaping and reduced distortion, thereby enhancing the converters' ability to handle high-resolution and wide-bandwidth signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional Nyquist-rate converters are used to achieve high instantaneous bandwidth, then the bandwidth can be increased, but the resolution deteriorates due to quantization noise and practical implementation impairments
Solution Approach 1:
The converter is divided into multiple parallel sub-converters (e.g., 5 sub-converters), each operating at a lower sample rate and processing a specific frequency band. This segmentation allows each sub-converter to achieve high resolution independently while the parallel combination provides extended instantaneous bandwidth, resolving the contradiction between bandwidth and resolution.
2Measurement precision
If oversampling converters are used to reduce quantization noise, then the resolution can be improved, but the instantaneous bandwidth is limited by the high sample rate requirement
Solution Approach 1:
Instead of using a single high-speed oversampling converter, the system segments the bandwidth into multiple bands and uses parallel sub-converters operating at lower sample rates. Each sub-converter performs oversampling for its specific band, achieving high resolution without requiring the entire system to operate at the high sample rate needed for full bandwidth coverage.
Solution Approach 2:
The system transitions from a single-dimension approach (single high-speed converter) to a multi-dimensional approach by adding the frequency band dimension. Multiple sub-converters process different frequency bands in parallel, effectively using the frequency dimension to achieve both high resolution and wide bandwidth simultaneously.
3Speed
If flash converters are used to achieve very high instantaneous bandwidth, then the bandwidth can exceed 10 GHz, but the resolution is limited to about 9 bits due to practical implementation impairments
Solution Approach 1:
The flash converter approach is segmented into multiple parallel sub-converters, each operating at a relaxed sample rate. This allows each sub-converter to achieve higher resolution (more than 9 bits) by reducing the impact of clock jitter and thermal noise, while the parallel combination maintains the high instantaneous bandwidth capability.
Data Source
AI summary
Provided are, among other things, systems, methods and techniques for converting a continuous-time, continuously variable signal into a sampled and quantized signal. According to one representative embodiment, an apparatus includes multiple quantization-noise-shaping continuous-time filters, each in a separate processing branch and having an adder that includes multiple inputs and an output; an input signal is coupled to one of the inputs of the adder; the output of the adder is coupled to one of the inputs of the adder through a first filter; and the output of a sampling/quantization circuit in the same processing branch is coupled to one of the inputs of the adder through a second filter, with the second filter having a different transfer function than the first filter.