Environmental Engineering Reference
In-Depth Information
By adopting this compensation network the output swing turns out to be
completely preserved. In addition, we shall exploit the finite output
resistance of the voltage follower to perform some simplifications as
described below. Denoting this output resistance as
the loop-gain transfer
function is modified to
Relationship (5.89) includes one dominant LHP zero and a RHP zero that
is now shifted to a very high frequency (since it is multiplied by the stage
gain Moreover, there are two non-dominant poles which are real and
negative under the condition (in practice usually met) These
two poles are well approximated by the terms inside the square brackets in
the second expression of (5.89). We can use the output resistance of the
voltage follower to obtain some forms of simplification, and among the
possible alternatives, we can set the value of this resistance equal to the
transconductance of the last stage
