A Ku-Band 13 W GaN HEMT Power Amplifier MMIC with a Coupled-Line Interstage Stabilization Technique for Radar Sensor...

Area of Science:

• Electrical Engineering
• Microwave Engineering
• Semiconductor Devices

Background:

• Ku-band radar systems require high-efficiency and stable power amplifiers.
• Multistage Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT) Monolithic Microwave Integrated Circuit (MMIC) amplifiers face challenges with low-frequency instability and process sensitivity.
• Conventional stabilization circuits can limit performance and robustness.

Purpose of the Study:

• To present a novel coupled-line interstage stabilization technique for Ku-band GaN HEMT MMIC power amplifiers.
• To improve the stability and robustness of multistage amplifiers against process variations.
• To enable efficient and stable power amplification for radar sensor front-end applications.

Main Methods:

• A two-stage power amplifier was designed and fabricated using a 0.25 μm commercial GaN HEMT MMIC process.
• A coupled-line interstage network was employed for stabilization, replacing traditional methods.
• The coupled-line structure was meandered for compact implementation and verified via electromagnetic simulations.

Main Results:

• The fabricated MMIC demonstrated stable operation without oscillation across the 13.5-16 GHz frequency range.
• Measured small-signal gain (S21) was 18.6-21.6 dB, with return losses S11 and S22 within acceptable limits.
• Large-signal tests yielded a saturated output power of 40.7-41.5 dBm and a power-added efficiency of 21.3-28.1%.

Conclusions:

• The coupled-line interstage stabilization technique effectively suppresses low-frequency gain and enhances robustness.
• This approach maintains excellent RF performance while mitigating process sensitivity in Ku-band GaN HEMT MMIC power amplifiers.
• The developed MMIC is suitable for demanding Ku-band radar sensor front-end applications.