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wjxcom

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HI,all, I read a book about SINGAL AND SYSTEM. Now, I have a question: the phase and amplitude of the h(t) is decided by the zero point of the transition function H(s), and the pole point of the transition function H(s) can only decides the form of the wave of the h(t) . So, if we think about the stabilization of a system, we should analyse the pole point rather than the zero point.

I do not know the idea is right or not!!

please help me!!
 

I don't know if I understood the doubt you had , anyway I will try to answer.

The stability in H(s) depends only of poles, if all poles is in the left side of the s plane the system is stable, if you have any pole in the right side the system is unstable. Zeros don't matters for stability, unless you have to take the inverse of the system, if so, in order to have a system causal and stable, it is necessary that all zeros and poles are in the left side of the s plane, such systems are called minimum phase.
 

Hi, claudiocamera: thining the stability of a OP is thinking the phase of a OP, so since zoro point deside the phase and amplitude, why we analysis pole point rather than zero point?
 

For a system, poles in the right plane of the quadrant will affect the stability of the system.
But for an opa, poles in the right plane and zeros in the left plane of the system will affect the stability of the opa. For an opa in a feedback system, you also conside the relationship of GB and Phase margin which are related to both poles and zeros.

For details, see some reference books for signal and system , analog design books.
 

wjxcom said:
Hi, claudiocamera: thining the stability of a OP is thinking the phase of a OP, so since zoro point deside the phase and amplitude, why we analysis pole point rather than zero point?
Click to expand...
Hi wjxcorm, I am not expert in OpAmp, so I don't know wht a zero in it means. The explanation I gave was related to Linear Time Invariant Systems, regarding stability analysis and Laplace transform.
 

The zeros are the roots of the the numerator of your transfer function.
The poles are the roots of the denominator.
 

I don't know whether your statementthe "phase and amplitude of the h(t) is decided by the zero point" is true, but for OPAMP, it's not true that "we analysis pole point rather than zero point". Actually, we analysis both poles and zeros. OPAMP stability is judged by the phase margin or gain margin, both poles or zeros will contribute (different) phase shift thus affect the margin. You can refer to some reference book like Razahvi's.
Regards,
 

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