How can I characterize gm vs W/L in ltspice. Can anyone provide the testbench explaining the proper steps?

I've tried to sweep inductance in my sim. I give value for inductor {Lsweep} and put directive .param Lsweep (1u+(200u-1u)*({time}/1m)) on the schematic, but it don't work?

Hello My PLL is suffering from error signal DC drifting over time. I have built a PI controller AC responce and pulse responce shown below. The main this I want this controller to do is to keep the error sinal on the same DC level and make it stop drifitng. In PLL we set the error signal to "travel" around 0V . unlike regular amplifier when we have input and output , where I can see how CW signal will be amplified. In my case I dont know how the PI controller will handle the DC drift of my pll. Is there a way to do something in LTSPICE? Also I added some videos from the lab so you could understand the drift situation I got and in general the situation. Thanks. https://groups.io/g/LTspice/photo/294510/3866694?p=Created%2C%2C%2C20%2C2%2C0%2C0 https://groups.io/g/LTspice/photo/294510/3866693?p=Created%2C%2C%2C20%2C2%2C0%2C0 https://groups.io/g/LTspice/photo/294510/3866695?p=Created%2C%2C%2C20%2C2%2C0%2C0 20241215_095809000_iOS.MOV 20241215_091630000_iOS.MOV 20241215_091146000_iOS.MOV 20241215_090423000_iOS.MOV 20241215_082307000_iOS.MOV

Hello, In a diode rectifier circuit, the rectified signal is then filtered by a filter capacitor connected in parallel. How to calculate the minimum value of the filter capacitor by LTSpice? See my rectification-filter.asc file.

... No one has come up with the real reason for this behavior: I run a simulation where a resistor has a value of 51.7K. The first 30% or so of the simulation completes in the blink of an eye then slows down to 25ns/s. If I change that one resistor value to 51.71K, the whole simulation completes without a hitch! Why does adding 10 ohms, a less than 0.02% change in value in this case, make such a difference? This doesn't just apply to LTspice - it's been something people have complained about since Berkely SPICE was invented. I've yet to hear anyone give one definitive answer. Sure, in my case, this is no big deal, except when I try to step the resistance value or run a Monte Carlo analysis on the circuit. If that particular resistance hits the magical 51.7K, the whole thing comes to an essential standstill. Any thoughts, anyone? Thanks, John

Hi I am a new member here.Would be grateful if someone can direct me to the Varistor simulation files. Warm regards Ashish Roy

I'm looking for a sub-circuit or model for a varistor. The part number I need is MOV-07D43K but if anyone can point me in the right direction to find a generic varistor model or sub-circuit that I can modify that would be awesome! Thanks!

Hello, I have built a PI controller as shown in the photos below. It was taken from a manual. They say that 1Tera ohm was needed to be added so the simulation whould run properly and give more accurate result. How can I know in what case I need to add such large resistor ? Thanks. https://groups.io/g/LTspice/files/z_groups.io/Files-sorted-by-message-number/msg_ZZZZZZ/john23%20%232/1.zip

How can I create a voltage source in LTspice where I want the pulse to be modulated with a sine wave?

Hi all, I am a little stumped on how to appropriately model the combination of an input filter and converter power stage for use in determining whether the Middlebrook criteria are met. Here is my best attempt at a simulation; I have made a Comment for what I plotted that I think would be used to determine Middlebrook compliance: https://groups.io/g/LTspice/files/Temp/Filter_and_Converter_Middlebrook.zip I based how I set up this simulation on this paper (which is of course based on Middlebrook's): https://premiermag.com/wp-content/uploads/2022/01/H2PToday1911_design_TexasInstruments_part10.pdf Specifically, Figures 4 and 8 were my guide. Any help is greatly appreciated, -M

Thanks, I am new here. I want to do some deep-learning neural network about circuit design. So I sought a python lib called PyLTSpice, in which a simulator called XVIIx64.exe is need to be invoked. It is normally in the trace "C:\Program Files\LTC\LTspiceXVII\XVIIx64.exe". I looked forward a lot in the Intnet, and asked for the chatgpt, that things like onced having downloaded LTSpice, it occure in the trace "C:\Program Files\LTC\LTspiceXVII\XVIIx64.exe" or "C:\Program Files(x86)\LTC\LTspiceXVII\XVIIx64.exe". But I can't find it or XVIIx86.exe in my entire computer. Since I cant get "C:\Program Files\LTC\LTspiceXVII\XVIIx64.exe", I changed the Python code # Force another simulatior simulator = r"C:\Program Files\LTC\LTspiceXVII\XVIIx64.exe" to # Force another simulatior simulator = r"C:\ProgramData\Microsoft\Windows\Start Menu\Programs\LTspice\LTspice.exe" for I thought maybe the new version simulator changed from XVIIx64.exe to LTspice.exe directly. But the code run failed. My computer is based on win11, and the LTSpice is normally working in my computer. How should I get XVIIx64.exe? Companion who wants to work AI circuit design such as ANN or AINN can contact too.

Hi all, I need some guidance regarding different models of Valves which are readily available from this and other Web sites. As an example, I have added 3 12AX7 models below. I am trying to get them to run in a very simple triode circuit by pasting them directly into a schematic as Spice directives. ... and then to understand why they are different, in syntax structure and in operation. I have changed the Triode symbol Attributes to .... Attribute is Value, Prefix is X, InstName is U1 and SpiceModel is 12AX7 ... other fields are blank. The first .SUBCKT below runs okay, but I do not understand the syntax eg BGG GG 0 etc.. I'm okay with the maths. I cannot find this info anywhere in the LTspice Help, or in my many searches of the Web. Maybe I'm searching the wrong terminology .... any advice please?? Why does the first .SUBCKT model run, but the second one does not. I get an Error message "Undefined subcircuit triodenh"?? Also, why is the syntax vastly different? eg +PARAMS etc?? Thanks, Ian .SUBCKT 12AX7 A G K BGG GG 0 V=V(G,K)+0.59836683 BM1 M1 0 V=(0.0017172334*(URAMP(V(A,K))+1e-10))**-0.2685074 BM2 M2 0 V=(0.84817287*(URAMP(V(GG)+URAMP(V(A,K))/88.413802)+1e-10))**1.7685074 BP P 0 V=0.001130216*(URAMP(V(GG)+URAMP(V(A,K))/104.24031)+1e-10)**1.5 BIK IK 0 V=U(V(GG))*V(P)+(1-U(V(GG)))*0.00071211506*V(M1)*V(M2) BIG IG 0 V=0.000565108*URAMP(V(G,K))**1.5*(URAMP(V(G,K))/(URAMP(V(A,K))+URAMP(V(G,K)))*1.2+0.4) BIAK A K I=URAMP(V(IK,IG)-URAMP(V(IK,IG)-(0.00058141055*URAMP(V(A,K))**1.5)))+1e-10*V(A,K) BIGK G K I=V(IG) * CAPS CGA G A 1.7p CGK G K 1.6p CAK A K 0.5p .ENDS *Ayumi Generic tube.lib.txt file .SUBCKT 12AX7 A G K XV1 A G K TRIODENH +PARAMS: LIP= 1.5 LIF= 0.000016 RAF= 0.076498 RAS= 1 CDO=-0.53056 + RAP= 0.18 ERP= 1.5 + MU0= 87.302 MUR=-0.013621 EMC= 0.00000111 + GCO=-0.2 GCF= 0.00001 + CGA=3.90E-12 CGK=2.40E-12 CAK=7.00E-13 .ENDS *Duncan Munroe Generic ENHtube.lib file .SUBCKT 12AX7 1 2 3 ; A G C E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(V(2,3)+VCT)/SQRT(KVB+V(1,3)*V(1,3)))))} RE1 7 0 1G G1 1 3 VALUE={(PWR(V(7,0),EX)+PWRS(V(7,0),EX))/KG1} RCP 1 3 1G ; TO AVOID FLOATING NODES IN MU-FOLLOWER C1 2 3 {CCG} ; CATHODE-GRID C2 2 1 {CPG1} ; GRID-PLATE C3 1 3 {CCP} ; CATHODE-PLATE D3 5 3 DX ; FOR GRID CURRENT R1 2 5 {RGI} ; FOR GRID CURRENT .ENDS TRIODE *duncan Munro ???????

Trying to simulate a microphone capsule, which capacitance varies sinusoidally. LTspice rejects my syntax. File globalrecordsRF mic.asc uploaded to Temp

Hello everyone, I am in need of te LTSpice symbol for the TLV9062SIRUGR TI part. I can't seem to find it on this site and any help would be greatly appreciated. Thanks!

I am trying to create a negative voltage rail using a zener diode for driving a MOSFET. I've read several placed online about using a zener diode for this purpose but I cannot seem to get it to work. I am simulating using LTspice but the negative rail just isn't there. I would be very grateful if someone can help me with this and also understand what I'm doing wrong. This seems like something that should be easy but I'm missing something. I uploaded the file MOSFET Driver with Negative Rail.asc

Hello everyone, Why is it that I can't view anything smaller then 94ps? I tried confining the simulation run time to the waveform I wish to view and decreased the time step thinking that would give me more data, but no it didn't work.

Hi everyone, I inherited yet another design. This time, the LT3845A IC is being used as part of a buck converter. I am struggling to get this design to close in simulation with the part values I was given from a board that was actually built. The part values and surrounding circuit topology are most accurate in the LTSpice files (in the LTpowercad I had to fudge a little bit). At this point, I am not sure how it produced a steady output voltage in the lab. I have to provide simulation proof that the design closes (meets certain requirements) for customer purposes, if there was a question as to why I do not simply move forward with the lab data. https://groups.io/g/LTspice/files/Temp/LT3845A_sims.zip Right now I have two main concerns. (1) In the LTpowercad II simulation, the transient response to a stepped load has an output voltage ripple so high that it almost reaches +/-Vin. I do see that the compensation values that were selected are not ideal so I will address this. But right now, from playing with the different components, it seems the 10uF x2 output capacitors have the biggest effect on whether the output voltage ripple goes crazy or not. What doesn't make sense to me is that in the real test data, the output voltage ripple is on the order of 10s of mV. Is there something I am doing wrong in how I have set up the Power Stage Design's output caps to give a result that does not match the lab data? Not sure if this tool is still supported so feel free to ignore this request if it is. (2) I cannot seem to get the LTSpice ac simulation to find a dc operating point. I have the standard recommended options as Spice Directives for the transient simulation, but these options do not seem to help in the ac simulation. In fact, the only thing that would get the transient simulation to work was including the Startup directive. Please let me know if more information is needed. Any help is appreciated! Thanks! -M

Hi Team , i M getting an errow when i try to simulate the circuit .Its saying unknown subcircuit called in . Can some one let me know what is wrong with the circuit. Regards, Vipin

Hi , I m using CD4060B model to generate the required waveform but facing issue when i try to generate the output by cascading output of one stage to another stage . Can anyone let me know what is wrong in the attached circuit .How can i cascade the output of first stage to another stage. Regards, Vipin

Hi: A page on the software I'm on about is seen here: https://kgmagnetics.com/Magnetic_Component_Design_Software but, alas, the good Colonel passed the middle of last year. Does anyone have or know where a copy might be found ? Best regards, Bill Perkins