Stability, Mounting, and Measurement Considerations for High-Power GaN MMIC Amplifiers.

Area of Science:

• Electrical Engineering
• Microwave Engineering

Background:

• On-wafer measurements of high-power amplifiers (HPAs) present stability challenges.
• Monolithic microwave-integrated circuits (MMICs) require careful design to prevent oscillations.

Purpose of the Study:

• To present a precise design of an X-band, three-stage GaN HPA.
• To discuss techniques for predicting and ensuring MMIC stability during on-wafer measurements.
• To analyze instabilities in both on-wafer and mounted chip measurements.

Main Methods:

• Design and simulation of a three-stage X-band HPA using GaN technology.
• Application of stability analysis techniques to predict and mitigate oscillations.
• Characterization of measurement results using stability criteria.

Main Results:

• A GaN HPA was designed and fabricated, achieving 42 dBm output power and 32% power-added efficiency at 20V drain bias.
• Critical design and measurement points leading to instability were identified.
• Simple analysis methods were validated for verifying amplifier stability.

Conclusions:

• The precise design and stability analysis of HPAs are crucial for reliable performance.
• Amplifier instabilities are frequently linked to measurement process errors or characterization issues.
• Stability techniques are effective tools for characterizing and validating measurement results.