On 7/23/06, Dave Tweed <pic@dtweed.com> wrote:
> Palaniappan C <palani@orizin.net> wrote:
> > Maximum power transfer theorem states that maximum power
> > is supplied to the load when load resistance is equal to output
> > impedance. so in that case , efficiency will be only 50% .
> >
> > But class C ,D  amplifiers claim more than 50% efficiency.
> > If we match impedance , will it reduce their efficiency ?
>
> Yes.
>
> But be careful about what "efficiency" you're referring to in each case.
>

One more question regarding output impedance, How to find out
output impedance of transistor/MOSFET output stage ?

I found two methods , so got confused.
Method 1: Use thumb rule Zo =  (Vcc * Vcc)/(2 * Poutput)
Method 2: By using values of transistor/MOSFET output capacitance,
Load inductance (inductance between Vcc & collector). I mean , the
output impedance is calculated by circuit parameters.


regards,
palani
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