Question about op-amp pole

[A.Anand Srinivasan]

as far as i know a pole is a point at which something goes to infinity...
but i learnt in op-amp a pole is introduced to frequency compensate it..
why doesn't gain of op-amp go to infinity at that frequency

 

[demodb]

Re: pole

i think you could say it does go to infinity, however you have the limiting power supply. If the power supply would be able to go to infinity an infinte gain could be achieved.

 

[neils_arm_strong]

Re: pole

A pole is not "something" where "something" goes to infinity.
Given a transfer function,a pole is that number which makes the denominator of tha transfer function zero.
You need to study Bode plots.Addition of poles causes the slope of the plot to decrease by 20dB/decade.That is why we add a pole

 

[v_c]

Re: pole

Pole is a "frequency domain" term related to any number of transfer functions one can derive using Laplace Transforms. The transfer function is usually written as a ratio of two polynomials \[N(s)/D(s)\] using the complex frequency variable \[s\]. As it was already mentioned, poles of the system are the values of \[s\] that make the denominator equal to zero, that is \[D(s)=0\]. The values of \[s\] are in rad/s -- units of frequency.

Physically, poles represent the natural frequencies of the system and are independent of the input excitation applied to the system. They represent how initial conditions decay in the system.

I hope this helps you out.

Best regards,
\[v_C\]

 

[Kral]

Re: pole

A.Anand Srinivasan,
As neils_arm_strong pointed out, a pole is the value of the root of the denominator that causes the transfer function to go to infinity. Remember, however, that poles can be, and quite frequently are, complex numbers. Complex numbers have a real and an imaginary part. If a pole lies exactly on the imaginary axis (the real part is zero), the gain will, indeed be infinite at the freuqnecy reqpresented by the pole.
Regards,
Kral