FET amplifier Biasing circuit

[Mabrok]

I am designing microwave power amplifier for C-band, my question how to design DC biasing circuit in ADS and how to connect it to transistor used?
I am using ATF-511P8 Transistor from Avago technologies

 

[dick_freebird]

The gate has to be held slightly negative in the cases
I have seen, and the right answer varies with temperature,
"make" tolerances and so on. One approach I have seen
is to sense the voltage across the drain impedance and
servo that through a poor-boy op amp to maintain a
constant drain current (against an external reference).

Of course if the load is only an inductor this fails. But a
50-ohm broadband (to DC) match, it could be OK. A
PA might not be wanting a Class A setup though.

If you have access to well matched devices then a
replica bias scheme could work out; co-locate a
second FET on the same heat rail, bias the drain
similarly (V) but into a DC load (R) and do the op
amp thing.

Aspects like phase noise want a low gate impedance
and of course a decently low noise gate drive amp.

What class of operation are you going for? This I
think will have a lot of influence over biasing, drive,
coupling.

 

[Mabrok]

I am going for Class A