Hello everyone, currently i'm simulating one GaN doherty mmic PA, since i'm new to doherty and mmic GaN PA is a new research in our lab. So hope to get some advice here.
1) as for the OMN of the main amplifier, do i just match for the maximum power(match Zopt to 50ohm)? Or at the same time, the maximum PAE point should be matched to the 2*50ohm to get the best backoff efficiency? I tried to match them all but found difficult and the maximum PAE point always lines in the left part of smith chart. So is matching maximum PAE point to 2*50ohm a must-do step?
2) To get more obvious backoff efficiency enhancement, one driver stage is added before the main&auxiliary PA. It is interesting that backoff efficiency enhancement can only be observed
at center frequency but not in other frequencies. I changed a wide-band driver but in vain. So is there some noteworthy tricks in driver stage design in doherty mmic?
Any response, idea and papers recommendation is appreciated!