Environmental Engineering Reference
In-Depth Information
To conclude, the bandwidth of the dominant-pole compensated amplifier is
defined by the
second pole and the DC open-loop gain.
As we shall see in
the next paragraph this condition does not hold for the Miller compensation
strategy.
5.2 MILLER (POLE-SPLITTING) COMPENSATION
The well-known
Miller
effect can be efficiently exploited to perform
frequency compensation that for this reason is called Miller compensation or
pole splitting compensation. To understand its properties and design issues
consider the small-signal model in Fig. 5.2, which but for the presence of the
interstage capacitance
coupling the first and second stage, is equal to the
one in Fig. 5.1.
Neglecting for the moment capacitor
depicted in dashed lines, the
subject open-loop transfer function is
where the DC gain
is still given by (5.2) whose the coefficients are
