Phase Noise Correction Using an Auxiliary Oscillator Sampler
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Solution Overview
Problem
Discrete time receivers face significant challenges in reducing phase noise caused by internal oscillation systems and sampling clock jitter, which affects the accuracy of phase measurements in RF signals, and existing solutions are either complex, costly, or limited in application.
Innovation Solution
A phase noise correction system that uses an additional oscillator to evaluate and correct phase noise in the received signal, where the additional oscillator does not require precise tuning and can be external or internal, and the DUT and reference signals are oversampled by a factor of at least 2.5, allowing for effective noise reduction without the need for expensive oscillator improvements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If internal oscillators are improved to reduce phase noise, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
A digital signal processor acts as an intermediary to measure and correct phase noise mathematically, replacing the need for complex hardware oscillator improvements. The DSP analyzes phase noise characteristics and applies digital correction algorithms to compensate for oscillator imperfections.
Solution Approach 2:
The patent replaces mechanical/hardware oscillator improvements with digital signal processing methods. Instead of physically improving oscillator components, the system uses software-based phase noise measurement and correction to achieve the same measurement precision.
2Measurement precision
If a reference signal is digitized separately and converted into time stamps for correction, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the reference signal and DUT signal digitization into a unified process. Both signals are digitized simultaneously using the same ADC system, and phase noise correction is applied in the digital domain without requiring separate time stamp conversion mechanisms.
Solution Approach 2:
Instead of creating complex time stamp representations, the system uses direct digital copies of the reference signal that are processed alongside the DUT signal. This simplifies the correction mechanism while maintaining measurement precision.
3Device complexity
If synchronous sampling of DUT and reference signals is used, then device complexity is reduced, but adaptability decreases
Solution Approach 1:
The patent implements a dynamic sampling system that can operate in multiple modes. The system can switch between synchronous sampling for simple applications and asynchronous sampling with digital correction for more versatile applications, allowing adaptability without significantly increasing base complexity.
Data Source
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AI summary
Embodiments of the invention include a test and measurement instrument including a test signal input and a sampler coupled to the test signal input to generate a sampled test signal. The instrument also includes a noise reduction system that includes an additional oscillator coupled to the sampler and structured to generate a sampled oscillating signal, as well as a phase detector coupled to the sampled oscillating signal for measuring noise introduced by the sampler. The noise reduction system further includes a phase corrector coupled to the phase detector for removing the measured amount of noise from the sampled test signal. Methods of noise detection are also described.