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Loop and feedback analysis resources

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deep_sea

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Hi guys,
Can you recommend a good resource to understand the loop and stability analysis? I mean to master the loop and understand by intuition or by analysis the impedance seen by nodes and effect in feedback system not just understand the Bode plot and gain and phase margin.
 

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Dominik Przyborowski said:
Maybe the most popular Book
BTW Why you don't simply calculate quantities for a few cases? It is not a rocket science.
Click to expand...
Thanks for your reply. I mean by looking into circuit, how can I intuitively know the impedance seen and the Miller effect?
I think the right question is where can find several examples of loops.
For example, the attached current conveyor, what is the impedance seen by current source and the output of the opamp? Where to start if I am going to use small signal analysis.
 

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deep_sea said:
I mean by looking into circuit, how can I intuitively know the impedance seen and the Miller effect?
I think the right question is where can find several examples of loops.
Click to expand...
The best way is to learn, by calculating some general examples.
In general we can consider two different quantities - voltage and current, and depending to which one is used as input and output, there are 4 cases of loops.
Intuitively, the simplest one is series-series (voltage input and voltage output) as this is common for OPAMPs.
General theorem is provided by two-port network theorem and it should be described and explained in every text book on electronics.
deep_sea said:
For example, the attached current conveyor, what is the impedance seen by current source and the output of the opamp?
Click to expand...
The current source is connected to virtual ground, so even without any calculation you can say that this current source is seeing low impedance.
deep_sea said:
Where to start if I am going to use small signal analysis.
Click to expand...
With finite gain opamp - voltage controlled voltage source - Vout=K·(Vp-Vn). Use elements relevant for feedback (it means that rightmost branch is removed), replace MOSFETs with their DC small signal model (in this case simple Giacoletto's - voltage controlled current source shunting conductor) and use nodal analysis.
And at the end look on the terms multiplied or divided by K to find an effect of feedback (or directly calculated two cases - with and w/out feedback and compare).
 

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    deep_sea

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Dominik Przyborowski said:
The best way is to learn, by calculating some general examples.
In general we can consider two different quantities - voltage and current, and depending to which one is used as input and output, there are 4 cases of loops.
Intuitively, the simplest one is series-series (voltage input and voltage output) as this is common for OPAMPs.
General theorem is provided by two-port network theorem and it should be described and explained in every text book on electronics.

The current source is connected to virtual ground, so even without any calculation you can say that this current source is seeing low impedance.

With finite gain opamp - voltage controlled voltage source - Vout=K·(Vp-Vn). Use elements relevant for feedback (it means that rightmost branch is removed), replace MOSFETs with their DC small signal model (in this case simple Giacoletto's - voltage controlled current source shunting conductor) and use nodal analysis.
And at the end look on the terms multiplied or divided by K to find an effect of feedback (or directly calculated two cases - with and w/out feedback and compare).
Click to expand...
Thanks. This is very helpful. I found "Sedra, Smith" and "Jacob Baker" feedback chapter very useful.
 

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