Multi-Channel Oversampling ADCs for Wideband High-Resolution Conversion
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Solution Overview
Problem
Conventional analog-to-digital converters (ADCs) face limitations in achieving high instantaneous bandwidth and resolution due to quantization noise, clock jitter, thermal noise, and implementation impairments, which restrict their performance in high-sample-rate applications.
Innovation Solution
The use of Multi-Channel Bandpass Oversampling (MBO) converters with Diplexer Feedback Loops (DFLs) and Bandpass Moving Average (BMA) filter banks to improve quantization noise shaping and signal reconstruction, reducing phase and amplitude distortion and signal-processing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional flash converters are used to achieve very high instantaneous bandwidth, then bandwidth is improved, but resolution is limited by quantization errors from clock jitter and thermal noise
Solution Approach 1:
The converter is divided into multiple parallel sub-converters (first and second sub-converters), each operating at a lower sample rate but providing multiple output bits. This segmentation allows each sub-converter to achieve higher resolution while the parallel combination maintains high instantaneous bandwidth.
Solution Approach 2:
The invention transitions from a single-dimensional approach (single high-speed converter) to a multi-dimensional approach by combining multiple sub-converters operating in parallel with different output bit configurations, achieving both high bandwidth and high resolution through dimensional expansion.
2Measurement precision
If conventional pipelined converters are used to improve resolution through calibration and feedback, then resolution is improved, but instantaneous bandwidth is limited to less than 1 GHz
Solution Approach 1:
The pipelined converter is segmented into multiple sub-converters that can operate in parallel. Each sub-converter processes a portion of the signal, and their outputs are combined to achieve both high resolution and high instantaneous bandwidth exceeding 1 GHz.
Solution Approach 2:
Multiple sub-converters are merged in parallel configuration, combining their individual outputs to achieve resolution comparable to calibrated pipelined converters while maintaining instantaneous bandwidth greater than 1 GHz through the parallel processing architecture.
3Object-generated harmful factors
If oversampling converters sample at very high rates to reduce quantization noise, then quantization noise is reduced, but the raw converters can only provide low resolution (often single bit)
Solution Approach 1:
The oversampling converter is segmented into multiple parallel sub-converters, each producing multiple output bits instead of a single bit. This segmentation allows each sub-converter to provide higher raw resolution while maintaining the oversampling benefit of reduced quantization noise.
Solution Approach 2:
The invention changes the parameter of output bit configuration from single-bit to multi-bit per sub-converter. This parameter change enables each sub-converter to provide higher raw conversion resolution while the oversampling architecture continues to reduce quantization noise through high-rate sampling.
Data Source
Figure 1A~2
Figure 1B~1C
Figure 3A~3B
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 continuous-time quantization-noise-shaping circuits, 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.