CataM
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Hello everyone,
In order to have maximum power transfer, source and load impedances must be matched => results in 50% efficiency.
On the other hand, if we would increase the Load impedance with respect to the source impedance, efficiency is increased. This is the reason SMPS work, because the output impedance is small compared to the loads they power. Why isn't applied the same principle to RF PA ? Why don't just increase the load to say 100 times bigger than the source ?
Consider example:
Source (Vsource) --> source resistance (Rsource) --> load resistance (R)
efficiency (eta)=R/(R+Rsource) = x/(1+x) where x=R/Rsource. For x=100, efficiency close to 100%. Why don't apply a "lossless matching network" that increases the load resistance ?
Output Power = Vsource2*R/(R+Rsource)2 => if R>>Rsource, then all the power goes to the load, same as in SMPS. Why not apply this to RF PA ?
Thank you for your time !
In order to have maximum power transfer, source and load impedances must be matched => results in 50% efficiency.
On the other hand, if we would increase the Load impedance with respect to the source impedance, efficiency is increased. This is the reason SMPS work, because the output impedance is small compared to the loads they power. Why isn't applied the same principle to RF PA ? Why don't just increase the load to say 100 times bigger than the source ?
Consider example:
Source (Vsource) --> source resistance (Rsource) --> load resistance (R)
efficiency (eta)=R/(R+Rsource) = x/(1+x) where x=R/Rsource. For x=100, efficiency close to 100%. Why don't apply a "lossless matching network" that increases the load resistance ?
Output Power = Vsource2*R/(R+Rsource)2 => if R>>Rsource, then all the power goes to the load, same as in SMPS. Why not apply this to RF PA ?
Thank you for your time !