All Questions
Tagged with closed-loop stability
8 questions
2
votes
3
answers
134
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Why do we talk about system stability as a whole when Barkhausen criteria is valid only for one specific frequency?
The relationship AB=1 will be applicable only at a specific frequency. For instance, following is the bode plot for a circuit I have and as can be seen, the barkhausen criterion is met only at 6.3MEG ...
0
votes
1
answer
968
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How to determine the phase margin when the Bode plot never crosses 0 dB?
I have a graph that looks like this. I am tasked to measure the phase margin, but the graph doesn't exceed 0 dB.
The circuit is this. The input DC level is 0.6 V, which is the problem. When I change ...
0
votes
1
answer
144
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On the stability of differentiator based on OP amp with an example from TI manual
I am building a proportional-Differentiator circuit based non-inverting OP-amp. But I am confused with the stability condition of OP-amp.
The system will be unstable if the loop gain |T(s)|=|a(s)B(s)|...
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1
vote
3
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unstable systems with positive phase/gain margin
Open loop Phase/Gain margins provide information on how much margin the closed loop system have until it becomes unstable. In other words, how much you can increase the effective loop gain and or ...
- 61
1
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2
answers
1k
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Closed loop system stability with Bode
Stability of the closed loop system (with -1 feedback) can be assessed via Bode plot gain/phase margin analysis of its open loop system.
How can one deduce stability of the closed loop system directly ...
- 61
1
vote
1
answer
403
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Why is the slope of the op amp graph 20 log (AB) in this application note
I am going through the following guide for op amps :
http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf
On page 87 (screenshot attached) there is a bode plot which has got me slightly ...
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1
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3
answers
410
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What is the significance of phase margin in an open loop amplifier?
I know the importance of phase margin to ensure stability in closed loop systems, but what about in open loop systems?
I am designing a regulated common based LNA IC that operates in open loop.
Can we ...
- 305
4
votes
3
answers
648
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Circuit stable in the Bode diagram, unstable in step-response
I am designing a simple current control circuit and trying to simulate it in LT Spice. The circuit is not optimized for some real-world application, it's more a learning method for me to get grip on ...
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