Pulsed microwave photonic vector network analyzer based on direct sampling.

Area of Science:

• Microwave Photonics
• Electrical Engineering
• Measurement Science

Background:

• Active devices risk overheating under continuous wave stimulation, necessitating pulsed measurements.
• Pulsed vector network analyzers (VNAs) are crucial for characterizing devices without causing thermal damage.
• Existing pulsed VNA techniques face limitations in dynamic range and measurement efficiency.

Purpose of the Study:

• To propose and validate a novel pulsed microwave photonic vector network analyzer (p-MPVNA) based on direct sampling.
• To enable large dynamic range measurements of active devices under pulsed conditions.
• To overcome the overheating damage risk associated with continuous wave stimulation.

Main Methods:

• Direct sampling technique utilized for the p-MPVNA.
• Asynchronous wideband detection to receive pulsed signals.
• Undersampling with a low repetition rate optical pulse train to capture frequency components.
• Vector superposition of aliased frequency components to calculate pulsed S-parameters.

Main Results:

• The proposed p-MPVNA demonstrates a dynamic range decrease rate of 10log(duty cycle) for duty cycles below 10%, significantly slower than classical narrowband detection (20log(duty cycle)).
• Experimental validation using a 6 to 18 GHz microwave amplifier showed consistent gain curves compared to a commercial VNA.
• Pulsed S-parameter measurements of a 10 GHz low-pass filter confirmed the system's dynamic range behavior under pulsed stimulation.

Conclusions:

• The developed p-MPVNA effectively characterizes active devices under pulsed conditions, mitigating overheating risks.
• The direct sampling approach provides a robust method for pulsed S-parameter extraction with improved dynamic range performance.
• The experimental results validate the proposed p-MPVNA's capability for accurate and efficient pulsed measurements in microwave photonics.