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Questions tagged [ltspice]

Anything related to LTSpice. LTspice is a SPICE simulation, schematic capture and waveform viewer program from Linear Technology. LTspice is freeware with very liberal license, it is lightweight and isn't crippled in any way.

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23 views

Lt-spice switch model

I have a very simple circuit and want to see the current in the inductor. But I do not know why switch is behaving like that... Actually, I supposed to get KA range current. but it gives me very ...
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1answer
42 views

Creating a temperature-dependent solar cell in LTSpice (using varistors)

I'm currently working on my master thesis and therefore need to simulate a solar cell in LTSpice. I've already modeled and simulated some examples with constant values. But for a more accurate model, ...
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1answer
27 views

LTSpice: active load current generator soft saturation

I would like to use a current generator to pull down the voltage to zero (there is a voltage generator with a series resistor). The current generator models the output of a specific circuit, so it is ...
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1answer
46 views

Best place to report an LTSpice XVII crasher?

I have a small LTspice XV11 .asc file that reliably gives a SIGSEGV when I run the simulator under macOS 10.14.3 (Mojave). This is related to LTSpice IV for OS X (oct 2, 2018 version) crashes on ...
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2answers
47 views

Plot voltage for different resistor values in LTSpice

I've signed up for a SPICE course at work, that will take place on Monday and I'm desperately trying to learn electronics and SPICE. (I work as an embedded engineer but with very lacking electronics ...
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1answer
21 views

LTSpice predefined components for ideal Voltage Gain and Sum [closed]

I'm trying to enter a circuit found in a Book from C.P.Basso which contains: ideal gain stage with one input and one output (Vout=Vin*k) ideal adder stage, which has two inputs and one output (Vout=...
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1answer
66 views

Adding models in LT-SPICE

I have LT Spice the latest version XVII and I have tried to add some models from component supplies. I did it following instruction: I created 2 subfolders in library folder lib placed in My user ...
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30 views

How do I use a current source for a pulsed voltage in LT Spice?

For an LT Spice simulation I was doing of a transformer, I would like to set the current to 3 amps for a power supply, but I'm not sure how to use a current source for that. I tried putting two ...
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19 views

LTSPICE Model Parameters of P-MOSFET

I am trying to simulate a circuit including TSM500P02CX P-MOSFET. The manufacturer of the MOSFET doesn't provide SPICE Model, so ...
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2answers
33 views

Error in third-party SPICE subckt of a MOSFET

I am simulating my circuit having a DMG1012T N-Channel MOSFET in LTSPICE XVII. My Circuit is given below: However, after ...
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2answers
87 views

How to automatically “normalise” a voltage signal in LTspice?

I would like to create an output signal that is normalised by the maximum value of a signal in LTspice. This is to produce a signal between [-1, 1] that is suitable for producing a wave file like ...
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1answer
28 views

Help converting PSPICE .lib with multiple subcircuits to LTSPICE

I'm trying to convert an unencrypted PSPICE buck converter model (http://www.ti.com/product/LM2678/toolssoftware) from TI. I translated the top subcircuit based on these steps: https://www.analog.com/...
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1answer
27 views

Simple NMOS simulation error. High voltage drop across the nmos when trying to make a MOSFET switch

I have this simple NMOS configuration in ltSpice. I would imagine that when V2 (Vg) goes high, Vds would go close to zero. But this simulation suggests that there is a very high voltage drop across ...
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2answers
52 views

Permanent magnet synchronous motor (PMSM) equivalent circuit

I am trying to model a PMSM (permanent magnet synchronous motor) in LTspice and in order to do so I need to form an equivalent circuit. Through some research I believe the circuit should be formed in ...
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0answers
24 views

How to convert maxim MAX9650 pspice file to LTspice compatible file?

I am trying to simulate the opamp MAX9650 in ltspice with the model provided here: https://www.maximintegrated.com/content/dam/files/design/tools/modeling-simulation/pspice/MAX9650.FAM I changed the ...
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1answer
29 views

Adding dependant sources in LtSpice (CDCS)

I have the following schematic of the circuit, I wanted to added I2 as a Current Dependant Current Source depending on current on in V1 as three times the value, or, I(I2) = 3I(V1) I have tried ...
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1answer
32 views

LTC3588-1 circuit model LTSpice export

I would like to use the LTC3588-1 component native to LTSpice in SIMetrix, however I am struggling to find a way to handle the export/import. Is it possible to export a component from LTSpice in a ...
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2answers
98 views

Ideal DC Transformer in LTSpice

I am conducting some simulation work where I would like to incorporate the LTC3588-1 component model in LTSpice. I have an electrical model of a physical system that requires the use of an ideal DC ...
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1answer
71 views

Confusion with Bode plot in LTspice when using a voltage regulator

To experiment(out of curiosity) the effect of a low pass filter for an SMPS switching noise I wanted to try a filter where an LC cascaded by a linear regulator as shown in below diagram, I obtained ...
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3answers
101 views

Why am I having “Time step too small” error for this circuit in LTspice?

When I run this circuit I get the following error: Unless I set R4 to around 1 Ohm the problem persists. How can I fix this issue?
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2answers
46 views

Trying to plot input and output resistance for a single BJT in LTspice

I'm trying to plot a single NPN transistors's own input and output resistances in common emitter configuration looking into the base from input and emitter. I showed below with arrows that the plot I'...
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1answer
25 views

LT Spice Automation and automatic Plot data extraction

I am trying to automate LTspice from Matlab. I am running Lt spice netlist which is creating the .raw file. But I am unable to automatically extract the polt data after that. Any solution on how to ...
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2answers
60 views

TSMC model for lt spice simulation [closed]

From where to download the tsmc model file for nmos(slow,fast,typical) and pmos (slow,fast,typical)?
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1answer
24 views

Simulating process variations

How to simulate Drain current vs Drain source voltage characteristics of a NMOS with respect to process variations in LT Spice?
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1answer
33 views

LTSpice - Capacitor Charging/Discharging Circuit not working right

I am trying to do a charging and a discharging Circuit. R8 is the load that Capacitor C1 needs to discharge into when P12V_IN is low. My question is Why is Vsolenoid low in the interval shown on the ...
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1answer
80 views

DC/DC converter from 9V to around 180V - LTspice simulation

I am trying to simulate circuit from link: Nixie power supply, but I have come into some problems. I downloaded MC34063 from this forum and example in package is working perfectly. Below is my circuit ...
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1answer
26 views

LTSpice - PMOS Gate not turning on

My question is why is the M2 PMOS FET not turning on when Vchrg_ctrl is LOW? My problem is Vload never goes high to charge the Capacitor C1. I think I am missing something very silly here. Thank you ...
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2answers
42 views

Comparing differential-ended and isolation amplifier outputs for an “unbalanced” source input

I tried to simulate the effect of common-mode interference on unbalanced sources for three different inputs: single-ended, differential-ended and isolated. Below I inject a 1V common-mode voltage to ...
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0answers
27 views

Supply independent current reference

Given is the circuit for supply independent current biasing. What are the spice models that should be used in place of nmos and pmos so thay we get the desired output? It is required that the aspect ...
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0answers
57 views

Negative voltage supply

I've been trying to make a active load that would use a very small resistor, around 10mOhm as a shunt resistor. I've figured out how to make it, it's a common circuit, however since I need to use ...
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1answer
34 views

Confused about this simple Comparator Circuit Output Waveform

Below is my Circuit and Voltage Waveforms for the Comparator Circuit. My question is -- In the Highlighted area in the waveform - why is the V(CMP_OUT) not high since inp_u2 (blue) is higher than ...
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1answer
57 views

LTspice not giving correct output

I'm trying to make a negative voltage power supply, mainly for opamps. I did some googling and found a circuit I like, so naturally before making it, I wanted to simulate it first. It has 12V on the ...
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1answer
54 views

LTSpice - Voltage Comparator not working

My question is - why is CMP_OUT not going to HIGH (i.e. to 12V, P12V_IN) when INP_U1 is greater in voltage than INP_U2. I think I haven't wired the LT1011 right. Do I have to do anything with the "B" ...
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1answer
42 views

VCVS in LTSpice Operating as a Comparator

I am using a VCVS in LTSPICE. I am confused about the command in the Spiceline for using a Table. I want to use the VCVS as a 1 bit Comparator instead of making a transistor based one. What will ...
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1answer
53 views

MOSFET goes into saturation mode much later

I am using IRLML6346 NMOS in LTSpice. Its threshold voltage is Vt = 0.95V. I plotted the graph of Vds(voltage between drain and source) vs Ids(Current from drain to source) for different values of Vgs(...
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1answer
149 views

How to simulate constant current - constant voltage source in LTspice

I am trying to build the CCCV (voltage limited current source in LTspice, having following characteristics: Sources defined current until voltage at the terminals reaches defined voltage, then keep ...
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3answers
208 views

How to simulate the impedance for this LISN circuit in LTspice?

I tried to simulate the following simplistic LISN circuit: Below is the AC analysis with LTspice for two nodes: But these above plots do not tell me anything related to the purpose of LISN which is ...
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1answer
46 views

LT-SPICE subcircuit programming

I want to create a SPICE subcircuit file for an electronic component. I have found the Verilog A code for the component, I want to know how to convert the Verilog A code to LTSPICE compatible ...
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2answers
88 views

Confusion with “skip initial operating point solution” in LTspice

I'm trying to simulate the following boost converter to see Vout versus Vin: In LTspice if I run the simulation for the first 250ms I obtain this plot where Vout < Vin: But if I chose "skip ...
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1answer
180 views

How can I simulate an NTC on LTspice?

I have a schematic for a temperature controlled device which should operate at a particular temperature. For that I am using an NTC, now I have done the math by hand but it is more efficient and ...
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1answer
52 views

BJT LT spice DC transfer characteristic

Why is it that the DC transfer characteristic isn't flattening out at -5 v, so it looks like a Z-shape? I did a DC sweep from -10 V to +10 V. The input wave is a 2V sine wave for the graph below:
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2answers
107 views

Modelling 3-phase induction motor and filter for inverter output in LTspice

I am designing an inverter in Ltspice and am looking to have a simple circuit to represent the motor load and filter out the PWM harmonics in order to obtain outputs. The motor characteristics are: ...
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1answer
72 views

Need help with three-stage transistor amplifier in LTSpice

I am currently attempting to design an amplifier in LTSpice for an E1 project. My professor tends to emphasize analysis of these circuits, so he hasn't really given us any kind of a design process to ...
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1answer
44 views

How to do a transient simulation using LTspice? [closed]

I have the following circut that resembles a CMOS inverter. Now I want to do a transient simulation on this circut but I am not sure how to do it. I always get a straight line! Not sure why. I tried ...
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1answer
127 views

how to check the slope in a certain point in a graph in ltspice?

i have a graph in ltspice and i am trieng to find in which point the slope is -1 ? for example this graph : is there is a way to find out ? or i just need to guess ? thank you in advance ! ...
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2answers
48 views

how to plot two graphs on ltspice on the same y scale?

i want to plot more than one graph on ltspice , the first one shows the voltage vout according to vin , and the second one the derivative of vout to vin , but it shows the two graphs on two different ...
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1answer
73 views

Frequency dependent capacitor for AC sweep analysis in LTspice

I need to model a frequency dependent capacitor for AC sweep analysis in LTpsice. I see that it is possible for inductors with GLAPLACE component, but I don't find anything about capacitors. The value ...
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30 views

Plotting pulse width or frequency of a pulse train LTspice

Maybe I'm demanding from the tool too much but I'm wondering whether the following possible in LTspice. I have a PWL file(time and voltage values) which can be read and plotted by LTspice. This is a ...
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1answer
93 views

Best practices for using subcircuits and hierarchical blocks in LTspice

I'm designing a series of circuits in LTspice and wanted to get some feedback on the accepted way to use subcircuits and hierarchical blocks. The LTspice manual is somewhat vague on these topics. In ...
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1answer
30 views

Plot Stepped Measured Data is disabled at Spice Error Log LTspice

I'm following the example from the top answer of this question. Here below I exactly do the same thing: But when I right open Spice Error Log (View -> Spice Error Log), and right click on a place as ...