HI,
I am designing a 1~30MHz PA .The PA requires the output 130W and IMD3<-34dBc .The DC supply is +24V.
I chose the MHW592 ,MRF426 and MRF 422.But the IMD3 cannot satisfy the request.
The tansistor is right?
thanks!
MRF422 is a 150W/28V transistor. From Motorola datasheet looks that it has approximately -36dBc at 130W but supplied at +28V.
I don’t think there will be more than 6dB degradation if you supply at +24V, but have to retune the output match for best IM3. Also try to increase a little bit the Icq quiescent current.
There are a few things to improve the linearity of a power amplifier including tuning of the: input/output matching network, bias decoupling, harmonics termination, etc.
Also beware when you measure intermods with the Spectrum Analyzer. The fundamental power shall not overload the SA input, because this will produce intermods internally, which will deteriorate your results.