Environmental Engineering Reference
In-Depth Information
Since circuit in Fig. 6.15 represents a common Y configuration, it can be
analysed by using its equivalent model in Fig. 6.16, in which
and
are
defined in (2.21) and (2.11).
Then using relationships developed in paragraph 2.5 we obtain
which is a quantity always lower than one. Moreover, we can easily evaluate
the input and output resistance, and by using the results in (2.20a)
and (2.11), respectively. Note that to evaluate the input resistance we have to
consider the circuit scheme in Fig. 6.13
2)
To evaluate the return ratio we set to zero and replace the original
controlled current generator, with an independent one,
i
. Now, as
can be deduced from the equivalent circuit shown in Fig. 6.17, transistor T2
works as a voltage follower, and voltage
is a portion of the voltage at
node X of T2.
