An 18–44 GHz Power Amplifier in 90-nm GaN Using Active Impedance Matching

Abstract

This work presents an active impedance matching technique to extend the bandwidth of a power amplifier (PA). The architecture is similar to that of the load-modulated balanced amplifier, but employs phase-only control to avoid the complexity and gain compression characteristics associated with millimeter-wave load-modulated PAs. To evaluate the effectiveness of the technique and fully explore the design space, four monolithic microwave integrated circuit (MMIC) PA variants are fabricated and compared through measurements. Specifically, load-pull characterization of the best-case performance of the single-ended PA used in the active match balanced amplifier is compared to the overall active match architecture to identify and understand the sources of losses in the system. The primary active match design demonstrates a wideband operation from 18 to 44 GHz, with an output power of 28-31 dBm and a power-added efficiency (PAE) of 12–31% in continuous-wave (CW) measurements.