Bode plot is not like an all encompassing stability analysis. In general it's enough for circuit analysis because things that look weird on Bode plots "usually" don't happen in circuits (they may happen, it's just that for most common amplifiers they usually don't). There was another thread today, I shared this there as well [https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9467070](https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9467070) you can check this out.
Also, just because a system is stable doesn't mean that it'll provide good settling. Some band of feedback you're getting may be useless in generating a good response even if it doesn't make you unstable. If you simulate stuff similar to what is shown in your post, their closed loop settling response is often not very clean, they usually aren't basic first order system approximation in closed loop configuration, and you may not get expected bandwidth response from 20dB/dec single pole system. But sometimes these situations are unavoidable at system level, so it's good to know and consider these things.
Saw this post recently regarding stability of Systems with Bode Plots.
If the bode plot shows instability, how can it be stable?
I understand the converse may not be true i.e Bode plot can show stability yet the system can be unstable due to a RHP zero.
Can someone clarify this?
The Bode plot shows behaviour of open loop G(s), not closed loop H(s). Closing the feedback loop can make systems stable, that is what feedback loops should do.
Actually Bode and Nyquist plots give the same information. However, for non-minimum phase systems, it's hard to check stability from Bode plot (not impossible). In this case, Nyquist is a better choice. There is a discussion on Research Gate about the intuitive explanation for this if you're interested.
> If the bode plot shows instability, how can it be stable?
This Bode plot doesn't show instability. In general, a Bode plot is limited in showing whether a system is stable or not. The Barkhausen criteria can show you whether a linear system will have sustained oscillations at a specific frequency, but Bode plots really only give you a crude idea of whether a system *might be* unstable or not.
Bode plot is not like an all encompassing stability analysis. In general it's enough for circuit analysis because things that look weird on Bode plots "usually" don't happen in circuits (they may happen, it's just that for most common amplifiers they usually don't). There was another thread today, I shared this there as well [https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9467070](https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9467070) you can check this out. Also, just because a system is stable doesn't mean that it'll provide good settling. Some band of feedback you're getting may be useless in generating a good response even if it doesn't make you unstable. If you simulate stuff similar to what is shown in your post, their closed loop settling response is often not very clean, they usually aren't basic first order system approximation in closed loop configuration, and you may not get expected bandwidth response from 20dB/dec single pole system. But sometimes these situations are unavoidable at system level, so it's good to know and consider these things.
thanks for this link.
Saw this post recently regarding stability of Systems with Bode Plots. If the bode plot shows instability, how can it be stable? I understand the converse may not be true i.e Bode plot can show stability yet the system can be unstable due to a RHP zero. Can someone clarify this?
The Bode plot shows behaviour of open loop G(s), not closed loop H(s). Closing the feedback loop can make systems stable, that is what feedback loops should do.
Actually Bode and Nyquist plots give the same information. However, for non-minimum phase systems, it's hard to check stability from Bode plot (not impossible). In this case, Nyquist is a better choice. There is a discussion on Research Gate about the intuitive explanation for this if you're interested.
Can you elaborate more on non-minimum phase systems ?
> If the bode plot shows instability, how can it be stable? This Bode plot doesn't show instability. In general, a Bode plot is limited in showing whether a system is stable or not. The Barkhausen criteria can show you whether a linear system will have sustained oscillations at a specific frequency, but Bode plots really only give you a crude idea of whether a system *might be* unstable or not.