Dual-ADC Nyquist-Zone Alignment for Wideband Dynamic Range
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Solution Overview
Problem
Conventional analog to digital converters face challenges in simultaneously achieving a wide dynamic range and wide band, often requiring multiple converters with different optimizations, leading to increased circuit complexity and cost.
Innovation Solution
The system employs a combination of analog to digital converters with different sampling frequencies and bit numbers, using a common frequency conversion means to produce digital data with a narrow dynamic range and wide band, and digital data with a wide dynamic range, by aligning the center frequencies of Nyquist zones and utilizing filters to extract suitable bands from an intermediate frequency signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single analog to digital converter is used, then the circuit complexity is reduced, but it cannot simultaneously achieve both wide dynamic range and wide band
Solution Approach 1:
The patent divides the frequency spectrum into multiple Nyquist zones and assigns different AD converters to different zones. The first AD converter handles the nth Nyquist zone with sampling frequency Fs1, while the second AD converter handles the kth Nyquist zone with sampling frequency Fs2. This segmentation allows each converter to be optimized for its specific zone, achieving both wide dynamic range and wide band coverage without requiring a single complex converter.
Solution Approach 2:
The patent introduces the dimension of Nyquist zone ordering to solve the contradiction. By utilizing different orders of Nyquist zones (nth zone for first converter, kth zone for second converter) and different sampling frequencies, the system expands the effective bandwidth while maintaining high dynamic range in each zone, thereby achieving wideband performance without requiring a single converter with excessively high sampling frequency.
2Adaptability or versatility
If multiple analog to digital converters are used with different optimizations, then both wide dynamic range and wide band are achieved, but the number of frequency converters increases leading to circuit complexity and cost increase
Solution Approach 1:
The patent merges the frequency conversion function into a single common frequency conversion means that serves both AD converters. The frequency converter converts the input signal to an intermediate frequency that can be processed by both the first and second AD converters. This merging eliminates the need for separate frequency converters for each converter path, reducing circuit complexity and cost while maintaining the ability to achieve both wide dynamic range and wide band through proper Nyquist zone assignment.
3Ease of operation
If different frequency converters are used for each path, then signals with different bands are provided to respective circuits, but circuit complexity and cost increase
Solution Approach 1:
The frequency conversion means is designed with universal functionality to serve multiple purposes. It can convert the input signal to an intermediate frequency that is suitable for both the first AD converter (handling nth Nyquist zone) and the second AD converter (handling kth Nyquist zone). This multi-functionality eliminates the need for separate frequency converters for each path, reducing circuit complexity while maintaining proper band matching for both converters.
Data Source
AI summary
While combining AD converters that one is wide band but narrow dynamic range and the other is narrow band but wide dynamic range, it allows settings to provide a common intermediate frequency signal to the AD converters. A first BPF 50 provides a first AD converter 54 with the output signal obtained by getting an intermediate frequency signal Sif through a first band in the second Nyquist zone of the first AD converter 54. A second BPF 52 provides a second AD converter 56 with the output signal obtained by getting the intermediate frequency signal Sif through a second band in the third Nyquist zone of the second AD converter 56. At this time, the second band is set in the center portion of the second Nyquist zone band, and the first band is set in the center portion of the band of the intermediate frequency signal.