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Paul's Questions :Circuit Design



At 12:50 4/4/02 +0100, you wrote:
an amplifier has an open-circuit voltage gain of 200, an output resistance
of 10kohms and an input resistance of 500 ohms. the amplifier drives a load
of 1000ohms. sketch an equivalent circuit of the amplifier and determine the
following:
(1) the voltage gain;
(2) the current gain;
(3) the transimpedance;
(4) the transadmittance.
what is transimpedence and transadmittance?
are they just the same as impedence and admittance?
also, what voltage gain is it asking to be calculated? is it the closed loop
voltage gain?
this question baffles me
paul
I'll take a shot at this question off the top, as a penance for the
delayed feedback
on the transformer question.

Transimpedance and transadmittance.

The trans- prefix usually stands for transfer and it is part of the
standard jargon.
.In the context of a three or four terminal device, it is taken to refer to
a ratio of
a useful output quantity with respect to a specified input quantity.

I'd expect the transfer impedance of interest to be the value of an output
voltage
compared to the value of an input current.

You were asked for the voltage gain, given the open circuit voltage gain -
so the actual in circuit value is desired, I'd think.

Visualizing the simplest possible model: a 500 ohm resistance across two inputs
and a 10K resistance across two output terminals, the two coupled by
a gain element of X200.
If this output resistance is connected to a 1K load resistor, the open
circuit gain is reduced
.to a lower value representing the potential divider.

That's as much as I can offer for now - off to work.
Good luck!