Residual Phase Noise Measurement via Digital Carrier Suppression
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Solution Overview
Problem
Conventional residual phase noise measurement techniques face challenges in measuring broadband devices due to limited broadband phase shifter options and the need for specific mixer configurations, which complicates the design of automated systems and requires additional calibration steps, leading to inefficiencies in determining residual phase noise.
Innovation Solution
A system that uses phase-coherent signal sources and receivers to mathematically suppress the carrier signal, eliminating the need for physical mixing and signal processing components like mixers and amplifiers, by generating a reference signal phase-coherent with the stimulus signal and adjusting its phase and magnitude to cancel the carrier, thereby determining residual phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional physical mixing components (mixers, phase shifters) are used for carrier suppression, then measurement capability is achieved, but device complexity and calibration requirements increase
Solution Approach 1:
The patent replaces physical mixing components (mixers, mechanical phase shifters) with mathematical signal processing operations. The carrier suppression is achieved through digital subtraction of the reference signal from the DUT output signal, eliminating the need for complex physical mixing hardware and reducing device complexity while maintaining measurement accuracy
Solution Approach 2:
The patent creates a mathematical copy of the stimulus signal through the reference signal path, which is then used to cancel the carrier component in the DUT output. This copying approach allows precise carrier suppression without requiring identical physical mixing paths, simplifying the overall system architecture
2Adaptability or versatility
If broadband measurement capability is implemented, then versatility improves, but phase shifter limitations prevent effective measurement
Solution Approach 1:
The patent eliminates the need for broadband phase shifters by replacing mechanical phase shifting with mathematical phase correction in the digital domain. The reference signal can be digitally adjusted to match any frequency, enabling broadband measurement capability without being constrained by the frequency limitations of physical phase shifter components
3Measurement precision
If additional calibration steps are performed, then measurement accuracy improves, but measurement time increases
Solution Approach 1:
The patent performs preliminary characterization of the DUT (gain, phase response) that can be reused across multiple measurements. This preliminary action reduces the need for repeated calibration steps while maintaining measurement accuracy, as the stored DUT characteristics are used to generate the reference signal for subsequent measurements
Data Source
AI summary
A system for measuring residual phase noise of a device under test (DUT) includes first and second signal sources, first and second receivers, and a processor. The first signal source generates a first signal to be input to the DUT as a stimulus signal and provides a second signal that is phase coherent with the first signal. The second signal source receives the second signal and generates a reference signal based on the second signal, which is phase coherent with the stimulus signal. The first receiver measures an output signal from the DUT responsive to the stimulus signal, and the second receiver measures the reference signal from the second signal source. The processor mathematically suppresses a carrier of the output signal by determining a difference between the measured output signal and the measured reference signal, and determines the residual phase noise of the DUT based on the difference.