Environmental Engineering Reference
In-Depth Information
The small-signal equivalent circuit of a three-stage amplifier including
nested Miller compensation is depicted in Fig. 5.7. Parameters
and
are
the
-th
stage
transconductance and output
resistance,
respectively.
Capacitors
represent the equivalent capacitance at the output of each
stage,
are the compensation capacitors, and
is the equivalent load
capacitor.
In the following we neglect the effects of the parasitic capacitances since
they are generally one order of magnitude lower than the compensation
capacitances. Neglecting second-order terms, the open-loop transfer function
of the circuit in Fig. 5.7 is expressed by
where
is the DC open-loop gain equal to
and
is the frequency of the dominant pole
Hence, the gain-bandwidth product,
of the amplifier is equal to
