#### xuexucheng

##### Full Member level 2

I have a question about lapalase transform and fourier transform.

if the TF is 1/(1+s), then this system is stable, and we change s to jw and get 1/(1+jw)

we can get the a-f and phase-f characteristic.

However, if the is 1/(1-s), then this system is unstable, and we change s to jw and get 1/(1-jw)

we can also get the a-f and phase-f characteristic.

the a-f characteristic of there two system is same. and just the phase is lagged or ahead.

what i can not understand is that dose the 1/(1-jw) system stable?

(1/(1-s) is unstable, but I can not find 1/(1-jw) unstable, why???)

dose this system exist ?

Oh, hope I express clear.