Design Of C-band Internally Matched Power Amplifier Using GaN HEMTs

GaN material possesses wide bandgap,high breakdown voltage,high power density,and other properties that can match the performance requirements of power devices in terms of high temperature resistance,high power,and high efficiency.This paper developed a miniaturized C-band GaN internally matched power amplifier with integrated power detection function,which was relied on the high power and high efficiency practical engineering application requirements of power amplifiers in satellite communications,radar detection,electronic countermeasures,and other communication systems.The power amplifier circuit topology has a three-stage cascaded amplification design.The final output matching network is based on the GaN HEMT device’s physical equivalent circuit architecture.The LC cascaded matching circuit architecture is used to realize the transformation from the real part of the fundamental impedance to the another real part,adjust the second harmonic wave and the fundamental wave to be in antiphase at the same time,so that the maximum swing of the fundamental wave voltage is raised to improve the power amplifier’s output performance.To reduce the insertion loss of the matching network,the output matching network is implemented utilizing a thin film circuit.The inter-stage matching network and the input matching network are incorporated into the integrated passive circuit to futher minimize device size.The second harmonic tuning network is attached to the input end of the final power cell to increase the efficiency of power amplifier by improving the distortion of the voltage waveform.The inter-stage fundamental matching network is a Chebyshev band pass matching network,which accomplishes the impedance transformation from 20Ω to 1.8Ω.An equalization network is added to the input matching circuit to assure the flatness of the device gain.Connecting the diode single-ended detection circuit in parallel with the output port of the final stage output matching network,which increases the power amplifier’s integration even futher.Finally,a customized test fixture for the power amplifier is created,and the final output matching network is debugged and optimized using an automated test platform.Under 28 V pulse drain voltage,the saturated output power is larger than 49 d Bm,the additional efficiency is greater than 50%,and the power gain is greater than 29 d B,detection voltage is greater than4.5V.The C-band internally matched power amplifier with high saturated output power,high efficiency,and high power gain output characteristics,has broad market prospects in satellite radar detection,electronic warface and other fields.