Environmental Engineering Reference
In-Depth Information
that gives a higher limit for the current follower input resistance. If this
condition is met, the expressions of the two zeros become
Choosing the highest value of defined by equality in (5.100), it can be
shown that is four times greater than Moreover, we have that if
which is a condition easily met in practice. Thus
the second zero and the third pole in (5.99) are allocated well above the
second pole, and do not appreciably modify the phase margin.
Finally, if
we have that
This means that the first zero
does not modify
but must be considered when evaluating the phase
margin which is
and is reduced to (5.82) if
Thanks to the action of the negative zero, the approach adopting a current
buffer is preferable to the one using a voltage buffer.
