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| Question about bandgap stability | ||
| Author addxjyx Views 11 Posted at 2008/8/27 00:59 [View In Forum] | ||
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Hi, allvdlyoy vdlyoy I don't know how to simulate whether the bandgap circuit is stable. I use such a way as the figure. I use a small step signal V. Then I run transient to see whether the output is stable. Does that method right? Why? Can someone tell me how to simulate whether the BGR is stable?vdlyoy vdlyoy I will appreciate for your reply!vdlyoy vdlyoy Thank you in advance! |
| Reply No. | Replier | Total Replies 13 [View All Replies] [New Reply] | Replied at |
| 1 | naoge | There's at least two feedback loops, one is positive and another one is negative. So they fight with each other. You might also try to step at the input, - input terminal of the OpAmp, and supply lines (something like CM step). |
2008/8/27 00:59 |
| 2 | htc2498 | Hi gte582w, You said my measure is right and I also need to add step signal at two inputs and supply. But someone said I should AC simulation which I am not good at. I am misunderstanding which method is right. Can somebody explain? |
2008/8/27 00:59 |
| 3 | scuzt | you should simulate the AC. Break the loop the input of the amplifer, put the ac input signal to the input of the amplifier, then you can get the phase margin at the e of the Q1 | 2008/8/27 00:59 |
| 4 | naoge | loop gain sim | 2008/8/27 00:59 |
| 5 | btcdtc | Hi pfd001, I have done as you said. But the gain is negative, the phase decrease from 0 degree. I don't know how much the phase margin is. I want to ask another question. You said I should put the ac input signal to the negative input of the amplifier. Can I put the ac signal at the positive input? |
2008/8/27 00:59 |
| 6 | z315 | you will use stb to do AC check of the loop gain and phase margin, but remember AC is small signal, therefore, I would trust ultimately the transient, that is why step the inputs and supply lines are must. |
2008/8/27 00:59 |
| 7 | fujun2013 | I think that you can test it by adding a step power supply and then do some transient simulation . | 2008/8/27 00:59 |
| 8 | nnxd | Search for the Thesis papers in edaboard.I have seen a paper long back which addressed these problems. | 2008/8/27 00:59 |
| 9 | zunwang | try two loop gain simulation | 2008/8/27 00:59 |
| 10 | spacebac | 2008/8/27 00:59 | |
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