GaN VHF Broadband Power Amplifier

I'm designing a 20-500 MHz power amplifier (100W)with GaN technology @ 28V Vdrain. I'm not sure if using 2 transistor in a push-pull configuration or using 1 transistor and microstrip, considering that GaN has a higher in-out impedances than LDmos. I'm thinking of using CREE or Nitronex devices,
any suggestion?
Thanks
Andrea

Well, good luck. These devices do have very low output impedances, so building a transformer over that bandwidth will be challenging.

Maybe you could do something unique and combine the output impedances in series somehow with a stackup. Lets say one device has 5 ohms output impedance. If you could design a structure to connect 5 of those outputs in series, you would have a 25 ohm impedance to match to the 50 ohm output. At these lower frequencies, maybe it could be done.

Hello Biff44,
you say: "combine the output impedances in series....If you could design a structure to connect 5 of those outputs in series..." how it could be possible? The final stage must not have more than two transistors otherwise I buy the amplifier

Hello Andrew77,
For this kind application, in NXP website there is a 120W application note with BLF645 from 10mhz to 600mhz, maybe you can take it as reference.
http://www.nxp.com/documents/applica...te/AN10953.pdf

if i wanna use the 145 MHz frequency
What do I need to set?
please help me
Regard:
_haryo_