HI,ALL,
I want to design a 10W power amp of a base station at 900M.
I found a HEMT PA and a LDMOS PA, and I am curious about at which PA I should select.
1st of all, mass production is the 1st priority.
Could you give some comments?
Thanks.
the LDMOS will probably be cheaper. the LDMOS has a very low output impedance, and large output shunt capacitance, which will limit the bandwidth it can be matched over. The GaN fet has a higher output impedance to begin with, and less shunt capacitance since the devices are physically smaller, so you can do higher frequency and bigger bandwidths.
If you're doing something standard like a 900MHz basestation, then you should be able to find reference designs from device manufacturers. I would look at those first, then compare the costs of each design, including supervisory circuitry (especially for HEMTs with negative gate bias). Don't worry so much about the underlying technology unless you're doing something novel.