Environmental Engineering Reference
In-Depth Information
polynomial depends on the specific input and output terminals. In particular,
it is analytically given by the determinant of the minor defined by the input
and output node. Hence, for the common X configuration with degenerative
resistance we get
It is apparent that in the case where degenerative resistance is equal to
zero we find the same positive zero in (2.41), which also coincides with the
approximated dominant zero obtained through (2.50).
2.7.3 Common Y and Common Z Configurations
Both the common Y and the common Z configurations can be represented
by the transfer function
where the DC gain has already been derived in Sections 2.5 and 2.6. The
coefficients and that identify the system poles are the same as in the
common X configuration with the degenerative resistance. Indeed, the small-
signal network is the same as the one in Fig. 2.12b after short-circuiting the
voltage source. Regarding the numerator, we can again use the nodal
admittance matrix (2.48). In particular, for the common Y configuration we
get
which shows two zeros that can be complex and conjugated.
For the common Z configuration the numerator of (2.51) is equal to
which shows two real and negative zeros.
