Coupling question between two amplifier stages

Hello all,
I have a small question,
What is the optimum coupling method between two transistor stages at 100MHz?
Capacitive coupling? Or Transformer?
If the latter, how to implement it? and calculate turns ratio?

Thanks in advance,
Ahmad,

It all depends on type of amplifier. Power RF amplifier needs matching between the stages. It can be done by LP filter or transformer, for example. If it is small signal amlifier then the coupling can be RC or DC.

sometimes in samll singal amplifiers like LNA u need a matching circuit
but the coupling capacitor shouldnot affect the coupling coz the coupling capacitor should be RF short circuit , but u need a capacitors to match the two stages

so u need both coupling capacitor and a matching circuit for max power gain

khouly

Do you mean that i must put matching section between two stages?

i think yeah , u need matching network between the two satges

khouly

ahmad_abdulghany,

Is your design broad-band or narrow-band? Do you use resistive or inductive collector/drain loading? Is it an LNA or PA or buffer?

I guess there is no good general answer to your question "What is the optimum coupling method between two transistor stages at 100MHz?". It will depend on many things.

/Peter

I don't know what to say about it, it's in the range from broad cast FM, may be considered wide band, but mainly, i do care only in the range around 100MHz (say 95M to 105MHz)...

What will be the differece? anyway, it's for now resistive...

It's an LNA

Thanks for help,
Ahmad,