What is the frequency of AC signal?

[shanmei]

AC signal?

hi,

everyone, we always use ac simulation for thr opm to get the phase, gain charactristic, we add the singal source with a ac singal to the input of opm, but we never illustrate what the frequency of the ac signal .

so, what is the frequency indeed? For example, a 10M sinewave signal add to the input of the opm, but we simulation with ac, we never know what exactly the frequency is. It is queer.
someone can explian it ? thanks

 

[haff99]

Re: AC signal?

You don't need to specify a frequency because when you do an .AC analysis you are sweeping the frequency. That is why you need to input a starting frequency and an end frequency and how many points you want to calcuate per decade(if doing a logarithmic sweep). Therfore you are testing the op amp at many differnt frequencies in one simulations. Hence how you get your gain and phase plots(notice they are always plotted against frequency).

 

[manish12]

Re: AC signal?

it is like this

at 1hz : o/p1 = ?
at 2hz : o/p2 = ?

:
:
:
:

at last f hz : o/p(last) = ?


it means freq is increases and output recored

generally we specifies the range ac ana. will generate the o/p automatically .

above text just for explanation purpose .