A Harmonic-Suppressed GaN Power Amplifier Using Artificial Coupled Resonator

This brief presents an 11.5–17.5-GHz power amplifier (PA) with 32-dBm output power in a 0.25-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m gallium nitride (GaN) process. Capacitively and inductively coupled resonators are used for impedance matching to achieve a flat in-band power gain and a high out-of-band rejection. Meanwhile, the output matching network provides a second-harmonic suppression to improve the average efficiency within the bandwidth of the PA. The measurements show that the proposed PA exhibits an output power of 31–32.5 dBm and a power gain of more than 10.5 dB from 11.5 to 17.5 GHz. Due to the matching networks providing convenient dc feed and dc block, the chip dimension is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.1\times 1.1$ </tex-math></inline-formula> mm2, corresponding to a power density of 0.77 W/mm2. The proposed PA demonstrates a competitive fractional bandwidth and power density in GaN PA monolithic microwave integrated circuits (MMICs).