High-Efficiency GaN Frequency Doubler Based on Thermal Resistance Analysis for Continuous Wave Input

Compared to GaAs Schottky barrier diode (SBD), GaN SBD exhibits higher power handling capabilities and superior heat dissipation properties when used on high thermal conductivity SiC substrates. However, high-power continuous wave (CW) input causes a temperature rise and reduces performance in GaN-based frequency doublers. This article proposes a solution considering the thermal resistance of the SBD and using AlN as the dielectric substrate under high-power input. Furthermore, extending the metal to the ground minimizes assembly errors and guarantees consistency between simulation and experiment. The experimental results reveal the significant potential of GaN materials. With an input power of 646 mW in CW mode, a remarkable output power of 101.1 mW was achieved with only four anodes. Furthermore, at an input power of 440 mW, the frequency conversion efficiency peaked at 19% at 141 GHz. This notable achievement surpasses the performance of the existing GaN-based doublers and expands the operational capabilities to CW operation.