MT2000: Double Pulse Load Pull For Trapping Characterization Of GaN Transistors

Conventional continuous-wave (CW) and single-pulse load pull measurements often fail to capture the dynamic trapping effects that influence the real-world performance of gallium nitride (GaN) transistors. Maury Microwave's MT2000 RF Double Pulse Load Pull methodology addresses this challenge by separating device conditioning from RF measurement, allowing engineers to characterize GaN devices under controlled trapping and thermal conditions that closely resemble actual pulsed operation.

This application note explains how the MT2000 platform uses an RF pre-pulse to establish a defined large-signal operating point before a short measurement pulse captures critical performance metrics, including output power, gain, efficiency, and waveform behavior. By maintaining a consistent device history for every impedance condition, the system delivers repeatable, trapping-aware load pull measurements while minimizing the effects of self-heating.

The note also presents measured results comparing two GaN HEMT technologies, demonstrating how RF pre-pulse conditioning affects gain compression, back-off performance, and AM-PM distortion. Additional time-domain pulse profiling reveals current collapse, load-dependent compression, and other dynamic behaviors that conventional load pull techniques cannot observe.

By providing a more realistic view of device performance under high peak-to-average power conditions, the MT2000 helps RF engineers improve transistor models, reduce design uncertainty, validate emerging GaN technologies, and develop higher-performance power amplifiers for radar, wireless infrastructure, and other demanding RF applications.