Non-Uniform ADC Sampling for Higher-Bandwidth Oscilloscopes
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Solution Overview
Problem
Existing test and measurement instruments face challenges in handling high-speed signals due to the requirement for high-frequency sampling, which increases complexity and cost, and conventional sampling methods fail to efficiently recover original signals from fewer samples.
Innovation Solution
Implementing compressive sensing techniques in oscilloscopes to achieve higher bandwidth by using non-uniform sampling and L1 minimization methods, allowing recovery of original signals from fewer samples than Nyquist sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-frequency sampling is used to avoid aliasing and signal distortion, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the sampling parameter from uniform high-frequency sampling to non-uniform sub-Nyquist sampling. By varying the sampling intervals according to a pseudo-random sequence, the system achieves accurate signal reconstruction at lower sampling rates, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces the traditional mechanical approach of high-speed sampling with a computational approach using compressive sensing algorithms. Instead of increasing sampling hardware speed, the system uses signal processing techniques to reconstruct signals from fewer samples, reducing device complexity while maintaining measurement precision
2Speed
If high-frequency sampling is used to handle higher speed signals, then bandwidth is improved, but cost increases
Solution Approach 1:
The patent changes the fundamental sampling parameter from fixed high-frequency intervals to variable sub-Nyquist intervals based on pseudo-random sequences. This parameter change enables the system to achieve higher effective bandwidth without proportionally increasing sampling hardware requirements, thus reducing cost
Solution Approach 2:
The patent introduces a temporal dimension to the sampling process by using pseudo-random sampling sequences instead of uniform intervals. This dimensional change in sampling strategy allows the system to capture signal information more efficiently, achieving higher bandwidth处理能力 with reduced hardware cost
3Reliability
If uniform sampling at Nyquist rate is used, then signal reconstruction is reliable, but sampling rate must be twice the highest frequency component
Solution Approach 1:
The patent inverts the traditional sampling paradigm by sampling below the Nyquist rate rather than at or above it. By using non-uniform pseudo-random sampling intervals, the system achieves reliable signal reconstruction at lower sampling rates, improving productivity while maintaining reliability through compressive sensing theory
Data Source
AI summary
A test and measurement instrument includes one or more ports to receive a signal from a device under test (DUT), an array of analog to digital converters (ADC) to receive the signal, a data collector to output one sample from each ADCs during one ADC clock cycle, and one or more processors to provide a sample clock to each ADC having a different clock phase from other ADCs to cause non-uniform sample spacing at or below a Nyquist frequency, and to cause the ADCs to output samples with non-uniform spacing. A method includes receiving a signal from a device under test, providing a sample clock to each ADC in an array of ADCs having a different clock phase from clock phases provided to other ADCs causing non-uniform sample spacing at or below a Nyquist frequency, sampling the signal with a non-uniform sample clock, and outputting the samples with non-uniform spacing.