Digital Doherty schematics draft
This case study uses a state-of-the-art GaN Doherty amplifier, intended for 5G NR operation in the 3,5GHz range. Two groups of measurements were performed, linear and non-linear. These measurements are performed in the same test set-up, consecutively, and without a reconnection cycle. The test was driven, and measurement results were collated and post-processed, in the Matlab™ environment.
The linear measurements were performed by sweeping input power, amplitude and phase difference, at two different frequencies. The measured quantities were average output power, peak envelope output power, efficiency and linearity (ACLR). These are just example of metrics, others may be more appropriate, depending on the application. The sweeps were performed at two frequencies (low and high) using the manufacturer’s recommend Doherty biasing condition for class AB and class C.
Non-linear measurements were performed using a randomized shaping characteristic in the Auxiliary path, at the two frequencies, whilst also sweeping the (now) common bias point. (Between the class C and class AB used in the linear test phase.)
