Environmental Engineering Reference
In-Depth Information
5.5.2 RHP Cancellation with Nulling Resistors
Figure 5.16 shows the compensation network including two nulling
resistors, as customarily employed.
By using this network in the circuit in Fig. 5.7, the numerator of the open-
loop gain in (5.78) becomes
in which, as usual, only dominant terms are considered.
It can be shown that (5.83) provides real and negative zeros only with
complex matching between and (by setting one of the two
resistances equal to zero, it also is easy to verify that the RHP zero cannot be
eliminated as the coefficient is always negative).
A more effective solution is that shown in Fig. 5.17, which uses only one
resistor and leads to the following expression of
N
(
s
)
