Integrated Undersampler for Accurate S21 Channel Characterization
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Solution Overview
Problem
Existing digital sampling oscilloscopes (DSOs) face challenges in dense packaging environments and high-speed data transfer, as they can alter channel characteristics and require precise sinusoidal generation and measurement, limiting their applicability in measuring analog waveforms effectively.
Innovation Solution
The development of an undersampling method that integrates both the undersampler and receiver circuit on a single IC, using a phase mixer to shift sample clocks relative to the input signal, allowing for coherent or incoherent undersampling, and enabling the capture of S21 measurements without relying on precision sinusoidal generation or reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital sampling oscilloscope (DSO) probe is used to measure analog waveforms, then the signal can be captured and converted to digital values, but the probe significantly changes the characteristics of the channel and the analog waveform to be measured
Solution Approach 1:
The patent extracts the measurement function from the traditional DSO probe configuration and integrates it directly into the receiver circuit on the same IC. The receiver circuit includes an integrated sampler that can capture signal characteristics without requiring an external probe, thereby eliminating the harmful interaction between the probe and the channel while maintaining measurement capability.
Solution Approach 2:
The patent merges the receiver circuit and the sampler onto a single IC chip. This integration allows the measurement function to be built-in without requiring separate external probes, eliminating the probe-induced channel characteristic changes while preserving the ability to accurately measure analog waveforms through integrated sampling and processing.
2Measurement precision
If a network analyzer is used to obtain frequency response information, then S21 measurements can be constructed, but the approach is temporally serial and relies on precision sinusoidal generation and reception
Solution Approach 1:
The patent replaces the traditional network analyzer approach that relies on precision sinusoidal generation and temporal serial measurement with a digital sampling approach. The integrated sampler captures signal characteristics directly in the digital domain, eliminating the need for complex precision sinusoidal generation hardware while maintaining S21 measurement capability through direct digital representation and processing.
3Measurement precision
If full sampling is used to capture analog waveforms, then accurate signal representation is achieved, but the sampling frequency must be high and the system becomes more complex
Solution Approach 1:
The patent applies undersampling technique where the sampling frequency can be lower than the full sampling rate would suggest. By integrating the sampler with the receiver circuit and using digital processing, the system achieves accurate signal representation even at reduced sampling frequencies, thereby reducing system complexity while maintaining measurement precision through intelligent sampling and processing algorithms.
Data Source
AI summary
A periodic broadband signal can be used to determine the S21 measurement for a channel by stimulating the channel across a spectrum of interest. The channel response to such broadband signal can be measured from undersampled data captured at the receiver. The Fourier transform of the broadband signal as received, divided by the Fourier transform of broadband signal as transmitted, constitutes the S21. A physically contiguous IC can integrate both a receiver circuit, at which S21 is to be measured, along with an undersampler for sampling the received broadband signal. To maximize signal to noise, a pattern for the broadband signal can be selected to maximize the minimum power across the spectrum of interest. A pattern generator for the broadband signal can be integrated on the same physically contiguous IC with a multiplexer that can select either the pattern generator, or a typical source of data, for transmission into the channel.