Incorporating RF test measurements for efficient design flow of GaN-based power amplifiers

When designing an RF circuit using advanced non-CMOS device technologies, such as GaN (Gallium Nitride), component models are not always available or the provided models do not cover the operating conditions (frequency, bias, etc.) necessary for the application. Compact analytical models are also not available for these devices, and device sizes and bias conditions do not scale in the same way as CMOS devices. As a result, designers often need additional characterization steps to ensure that the utilized models are an accurate representation of the actual device behavior. In this paper, we present a design flow that incorporates RF tests that focus on design specific measurements. The goal is to minimize the number of these time-consuming measurements during the design process by utilizing interpolation between points in the design space that have already been explored and by initiating a new measurement only when exploring a point in the design space that falls far from all previously explored points. The design process is demonstrated in simulation on a GaN power amplifier (PA) that yields 42.9 dBm of signal power with only 0.5 dB of gain compression, 27.4 dB power gain, 28.3 % power added efficiency (PAE) and operates at a center frequency of 36 GHz.