I designed an RF amplifier that should amplify signals in the FM band of 88 to 108MHz. The circuit is as shown below:
The input to the circuit is connected to an USRP through an SMA cable. The output is connected to an half-wavelength (1.5m) dipole antenna. The input power is in the order of 50 to 100mW. The output which is close to 2W in my simulations is about the same power as the input in the real world. What is causing this?
Edit: I am actually using RD06HVF1 transistor. I am using the spice model for RD06HHF1 as the specs are identical.
Best Answer
the RD06HHF1? I could see HVF1 maybe at band III, but the RD06HHF1 is only specified to 30MHz!
You may want to have a look at the gate capacitance of that RF Mosfet, they are usually not small and need some input matching (Usually at least an L network, sometimes two stages if you want broadband gain).
Take a look at some of the designs for the 2M band, what you have will probably be unstable if you do manage to get meaningful gain out of it, layout is also everything in RF power amps, and again the ham 2M stuff will show you how it is done (Solid planes and the like).