Environmental Engineering Reference
In-Depth Information
As discussed in section 4.3, the second pole is often already defined and
the compensation task requires setting the dominant pole or, better, the gain-
bandwidth product,
Relationship (4.29) can be written as
hence, the required
implies having to solve the following third-order
equation
As particular cases, first consider the one where the pole-zero doublet is
derived from differential-to-single conversion. In this event doublet spacing,
is exactly equal to -1. By developing (4.42) in Taylor series around the
point
truncated to the second term, we get
which is sufficiently simple to be solved with pencil-and-paper.
In contrast, when the second pole can be moved to guarantee stability,
such as in the design strategy for cascode amplifiers proposed in [MN89],
from (4.41) noting that
we have to set
according to
