[Amps] Resonance in PiNetworks

[peter.chadwick at Zarlink.Com]

Eric said:

>In the case of an amplifier with a PINET tank, the most important of such
>quantities is the transmission coefficient of the network, which occurs at
the
>dominant resonance frequency.


This must be somewhat dependent upon one's definition of resonance. I've
always used the definition of the feed V and I being in phase (i.e. the
input impedance is resistive) , which means of course that low Q L networks
don't meet the definition of Xl=Xc: in fact, many of the definitions fall
down at low Q, or if applied to multi branched circuits. Strictly, the tank
effectively includes the output capacitance of the active device and any
shunt, such as the feed RFC: this can make quite a difference between
computed and 'real' values, especially at higher frequencies.

73

Peter G3RZP