Inward nonlinear characterization of Doherty Power Amplifiers

Doherty technique is widely sought for power efficiency enhancement through proper built-in load modulation. However, its implementation still lacks appropriate tools for detecting the sources of discrepancies between the simulated and measured performance. In this paper, a time-domain characterization technique is used to capture the individual nonlinear characteristics of the main and auxiliary amplifiers of a given Doherty Power Amplifier (DPA). This technique helped identify a significant input power dependent phase mismatch between the two amplifiers that was found to contribute to the overall distortions. Contrary to conventional characterization techniques, the inward characterization allows for capturing internal measurements data that provides insights on the operation of the DPA's building blocks and its troubleshooting.