Timeline for Floating node in LTspice
Current License: CC BY-SA 4.0
20 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 3 at 4:53 | vote | accept | Zahra_Alishah | ||
| Jul 1 at 7:46 | answer | added | Zahra_Alishah | timeline score: 1 | |
| Jul 1 at 7:40 | comment | added | Zahra_Alishah | You know I have to put the picture of simulation along with my calculation in Project work report. @winny but thank you very much actually I found my mistake, I had to connect the sources of M3 and M4 not their gain. (they are differential pair) | |
| Jul 1 at 7:31 | comment | added | winny | Still does not explain why you can't fix it so that the simulation converges. Your alternatives are hand calculation or potentially the alternative solver under Tools -> Control panel -> SPICE. | |
| Jul 1 at 7:23 | comment | added | Zahra_Alishah | because the question specifically provided the circuit and asked us to calculate only the value of I3 along with a few other parameters. @winny | |
| Jul 1 at 7:21 | history | edited | Zahra_Alishah | CC BY-SA 4.0 | add a new picture |
| Jul 1 at 7:20 | comment | added | winny | @Zahra_Alishah Why not? | |
| Jul 1 at 7:18 | comment | added | Zahra_Alishah | thanks for your suggestion, but I can not change anything except the value of current source I3! @winny | |
| Jul 1 at 7:16 | comment | added | Zahra_Alishah | thanks a bunch for your help, this question is from our university's Electronics 2 course, and our main reference is Professor Behzad Razavi's electronics book. I'd added the picture of original question. @Ste Kulov | |
| Jul 1 at 7:09 | comment | added | winny | What happens of you put 10 Mohm from VS3 to ground? | |
| Jul 1 at 7:08 | history | edited | winny | CC BY-SA 4.0 | added 2 characters in body; edited title |
| Jul 1 at 6:41 | comment | added | Ste Kulov | I'm not sure. I'm not very familiar with this type of input structure. Do you have a reference for it? The problem that the simulator is having is that the node Vs3 is not well-defined because it is floating. If Vs3 is connected to a current source which is connected to VEE=-10V, then there's no way for the simulator to determine the voltage at Vs3. Flagging the current source as load helps because it allows the current source to act as a resistor which prevents the current source and voltage source from fighting each other. | |
| Jul 1 at 6:04 | history | edited | Zahra_Alishah | CC BY-SA 4.0 | added 4371 characters in body |
| Jul 1 at 6:01 | comment | added | Zahra_Alishah | Surprisingly, when I increase the value of current source I3 to 1mA and enable tick "active load" for current source I1 as you said, it works without any error or even an infinite loop, but why? @Ste Kulov | |
| Jul 1 at 5:58 | comment | added | Ste Kulov | Oh ok. I believe then that the “Error” message is not the source of your problem. It’s attempting to do Gmin stepping so it looks like your simulation is failing to converge. If you open your LTspice .asc file in a text editor you can copy the text and paste it into a code block in your question. Then we can “download” your simulation and troubleshoot it further. | |
| Jul 1 at 5:48 | comment | added | Zahra_Alishah | Actually, when I ran the simulation, it didn't stop like before, so i used "halt", but in this time it didn't show me anything, so I don't know the error stayed on I1 or moved. @Ste Kulov by using ctrl+L, no error was shown! just said: Direct Newton iteration failed to find .op point. (Use ".option noopiter" to skip.) | |
| Jul 1 at 5:33 | comment | added | Ste Kulov | Did the error move to a different current source or did it stay on I1 after you made that change? | |
| Jul 1 at 5:11 | comment | added | Zahra_Alishah | thanks for your advice @Ste Kulov, but it didn't work. | |
| Jul 1 at 4:57 | comment | added | Ste Kulov | Right-click on I1 and click Advanced. Then under "Parasitic Properties" check the box that says This is an active load and then try again. | |
| Jul 1 at 4:38 | history | asked | Zahra_Alishah | CC BY-SA 4.0 |