# Capacitor, inductor and resistor - Poles and zeros

Discussion in 'Electronic Basics' started by Dummy, Sep 11, 2003.

1. ### DummyGuest

What are the roles of capacitor, inductor and resistor in creating
poles and zeros in an amplifier circuit for stabilization? Resistor
creates zero but capacitor and inductor create poles? How does the
addition of zero could increase the phase margin?

If we want to cascade two amplifiers, is there a need to design
matching network? Or it's enough to put the coupling capacitor between
two stages.

2. ### Jim ThompsonGuest

...Jim Thompson

3. ### John PopelishGuest

If you think of frequency response of a circuit as a two dimensional
rubber surface stretched over the S plane (+ and - sinusoidal
frequency in one direction and exponential frequency (decay and build
up) in the other, the points that have infinite response are referred
to as poles (as if the sheet were passing over an infinitely tall tent
pole at that point) and at points where the response is zero, are
referred to as zeros (as if the rubber sheet were thumb tacked down at
those points).

That is my run on sentence for the day.

The circuit elements that can be combines to produce poles and zeros
are many and varied, especially when you include gain elements. Your
generalities are wrong. I know of no such simple generalities to
replace them.  