Does the circuit without feedback have poles?

[Octago]

Hello Everyone,

the stability problem(such like poles and so on) normally only exists in closed loop circuit?

But if there is a circuit without feedback, does the stability problem still presents?
Are there still poles?

 

[dick_freebird]

There are poles in every circuit. The stability problem
comes when you turn those output poles into phase-shifted
input.

 

[Octago]

thank you very much

But could you please explain it in some more detail?

There are poles in every circuit. The stability problem
comes when you turn those output poles into phase-shifted
input.

 

[LvW]

Hello Everyone,
the stability problem(such like poles and so on) normally only exists in closed loop circuit?
But if there is a circuit without feedback, does the stability problem still presents?
Are there still poles?

Passive (and frequency dependent) circuits have poles with a real part which is negative (left hand side of the s-plane). Therefore they always are stable.
If such networks are used in active feedback circuits these poles change theit position and can move towards the Im-axis. As a consequence, the stability degrades. When the poles are on the Im-axis (real part zero) or even in the right hand half of the plane the circuit is unstable.