Microwave Photonic Vector Network Analyzer Using Optical Sampling
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Solution Overview
Problem
Current microwave vector network analyzers face limitations due to their limited bandwidth, complex architecture, high cost, size, and power consumption, particularly when measuring high-frequency signals, and suffer from issues like image rejection, I/Q balance, LO leakage, and DC offset.
Innovation Solution
A microwave photonic vector network analyzer utilizing optical sampling technology for direct sampling and frequency conversion, eliminating the need for superheterodyne or direct frequency conversion structures, thereby simplifying the system and expanding the measurement frequency range while reducing complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heterodyne frequency mixing is used to receive high-frequency signals, then measurement capability is improved, but device complexity, size, and power consumption increase significantly
Solution Approach 1:
The patent replaces the traditional electronic heterodyne frequency mixing system with a photonic-based measurement system. By using optical modulation and photodetection, the system achieves high-frequency signal measurement without requiring complex electronic frequency mixing components, thereby reducing device complexity while maintaining measurement capability.
Solution Approach 2:
The photonic local oscillator and optical modulation scheme enable the system to handle multiple frequency ranges and measurement scenarios through a unified architecture. The optical carrier can be modulated to generate various intermediate frequencies, making the system versatile across different measurement applications without requiring separate electronic mixing chains for each frequency band.
2Measurement precision
If multi-stage frequency mixing structure is adopted to achieve image rejection and high sensitivity, then measurement precision is improved, but system size and cost increase
Solution Approach 1:
The patent replaces multiple electronic frequency mixing stages with a photonic-based single-stage modulation and detection system. The optical carrier wave enables direct conversion of high-frequency signals to baseband through photodetection, eliminating the need for multiple electronic mixing stages and associated filters, thereby significantly reducing system size while maintaining measurement precision.
3Device complexity
If direct frequency conversion is used to reduce system volume, then device complexity is reduced, but I/Q balance and LO leakage problems are introduced
Solution Approach 1:
The patent uses photonic-based frequency conversion instead of electronic direct conversion. The optical modulation process inherently provides better isolation between I and Q channels through the orthogonal nature of optical carrier modulation, and the photodetection process naturally suppresses LO leakage. This substitution maintains low device complexity while improving signal quality and reliability.
4Device complexity
If traditional electronic receivers are used, then system structure is simple, but bandwidth is limited and high-frequency signals cannot be directly obtained
Solution Approach 1:
The patent replaces electronic receivers with a photonic-based receiver system. The optical carrier wave has inherently much higher frequency than electronic carriers, enabling the system to directly measure and process high-frequency microwave and millimeter-wave signals. The photodetection process preserves the high-frequency information, achieving wide bandwidth while keeping the overall system structure relatively simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances system bandwidth, reduces size and cost, and avoids image interference and other issues, providing a more efficient and precise method for measuring microwave devices' scattering parameters.
Implementation Method 1
A microwave photonic vector network analyzer utilizes optical sampling technology for direct sampling and frequency conversion
Implementation Method 2
a microwave source, wherein a signal loading module, an optical sampling module and a signal processing module are sequentially arranged along a signal output direction of the microwave source
Data Source
AI summary
Microwave photonic vector network analyzer and a method for measuring scattering parameters of a microwave device are provided. The analyzer comprises a microwave source, wherein a signal loading module, an optical sampling module and a signal processing module are sequentially arranged along a signal output direction of the microwave source; an output end of the signal processing module is respectively connected with a control end of the microwave source and a control end of the optical sampling module; and two test ports of the signal loading module are connected with both ends of a device to be tested. The invention realizes direct sampling and frequency conversion for microwave signals, abandons a superheterodyne structure and/or direct frequency conversion structure in the traditional network analyzer, simplifies the structure of the system while improving the measurement frequency range and avoiding image interference, and reduces system complexity, cost and power consumption.