# 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.

143 questions
53 views

### High Voltage Cascode with MOSFET LT Spice Simulation

I'm an electronics engineering student and want to develop a high voltage switch with normal Si N-MOSFETs. After some research, I discovered cascode switches for this application. Most of these ...
40 views

### Problem simulating LMP8645 current sense amplfiier in LTspice

Basically the problem i am getting is that the output offset voltage is extremely large (58mv) here is the datasheet for the amp: http://www.ti.com/lit/ds/symlink/lmp8645hv.pdf on page 9 it shows ...
200 views

### What's wrong with my input circuit? LTspice

I am designing my first power electronics board in LTspice to convert single phase AC to DC. This DC is fed to asymmetric bridge to drive an SR motor which is connected to a flywheel. This flywheel ...
167 views

### Nodal Analysis - solving 2 variables with 3 equations

There are three conditions: before the switch is closed (opened) while the switch is closed (closed) after the switch is closed (opened) I think I need to solve them sequentially, because the system ...
2k views

### LTspice, how to model a TLine

I am trying to do a simulation for a transmission line, I can draw below example circuit but got below two questions. How to do this step: .model TLine LTRA(...) ...
378 views

### Using SPICE to model dV/dt filter for inverter motor drives

I am starting to learn LTSPICE to create model where I can test various passive filter topologies for inverter drives where the output PWM has very short rise times and high switching frequency. I ...
5k views

### LTSpice Solar / photovoltaic simulation

I've been trying to simulate a solar cell with LTSpice to generate an I-V curve. The model I've been using is the simplified equivalent circuit model with a current source in parallel with a diode. ...
18 views

### LTspice - using save/load bias with a parameter sweep

I have a circuit which has some hard time converging in a DC simulation. The circuit does converge nicely in a transient simulation when skipping initial condition calculation. Therefore, I've ran ...
89 views

### In LTspice can I convert the units of an FFT which by default seem to be shown in dBV to dBµV?

In LTspice can I convert the units of an FFT which by default seem to be shown in dBV to dBµV? Cause of reason: The reason for this is that I've a modeled a LISN in LTspice where I want to simulate ...
532 views

### 3-Phase Inverter simulation

I'm trying to simulate a 3-phase inverter for BLDC(PMSM) in LTSpice. The problem is that drain current is way too high and also phase voltage isn't right. **New image *One leg If I put one source(...
152 views

### LTspice simulation of AD8421 instrumentation amplifier giving incorrect output voltages

I am trying to run a simple simulation of an instrumentation amplifier (AD8421, model from here) running on a single supply, but the output does not seem to be correct. The screenshot below shows the ...
210 views

### Importing transistor spice model to LTSpice not working

Using LTSpice XVII. I want to import the Diodes Incorporated ZXTP19020DG model. The SPICE model from their web site is: ...
88 views

### Improve mosfet spice model for LT spice solver

I have a SI7460DP spice model that I would like to use in a DC DC buck\boost converter (LT8390). I'm using the standard LT spice file generated by LT powercad (boost converter going from 12 to 15V). ...
201 views

### Can the directory/path on the schematics be disabled for the print in LTspice?

When you print preview from LTspice schematics the program automatically adds path/directory of the file to the bottom of the pdf. Not really a question directly related to an electrical engineering ...
66 views

### LTspice Hung Up For Certain Voltages?

I am running a transient model of a Type-E PFN circuit (probably not an important detail) and my processing time jumps from about 1 minute for one DC source voltage to roughly 475 years for another. ...
286 views

### How's this for an SSR LTspice model?

I probably need to use an SSR for a design. I have never used SSRs, I just know things that have read on data sheets and the internet. I am planning on using the following spice circuit for a model... ...
51 views

### irritation in LTspice

I have written some measurement commands in LTSpice to calculate the weighted harmonic distortion (PWHD) .meas a1n INTEG (I(Lgra)*cos(2*n*180*fg*time)) .meas an PARAM a1n*2*fg .... (if somebody ...
1k views

### LTspice unicode trouble with micro symbol

I am having a pretty simple issue with LTspice, I built my circuit and it works fine, but the units for the capacitors don't display properly and I get the that "fE" unicode error I guess instead of ...
2k views

### Use variable in SPICE parameter list

I'm using LTSpice XVII to try and simulate a circuit. I've created a schematic which uses a Pulse voltage source to simulate a rotary encoder as follows: As you can see in the PULSE component, I'm ...
113 views

### Modelling a LED Array for SPICE simualtion

I am currently looking to model a whole LED array within LTSPICE. I am working on all of hte logistics right now. I currently have a LED array with about 300 LEDs on the array. Instead of modelling ...
215 views

### Simulating varicap diode in LTSpice

I have been looking into making a voltage controlled oscillator using varicap diodes, however I have had hard time simulating the diodes in spice. Would anyone here have an idea how this would be ...
79 views

### Problem with Simulation Results VS Tested Results for a signal

For the circuit shown i am having some trouble wondering why my tested signal looks like this (i understand that it could be clipping) but when i measure my circuit in the simulation it is correct? ...
103 views

### How to interpret LTspice simulation outputs for improving dual channel boost converter design using LTC3788

I am working on a boost converter design using the LTC3788. I would like to take advantage of the dual output capabilities of this chip to produce 24 VDC at 4 amps on one output and 48 VDC at 2 amps ...
1k views

### MOSFET Parameters LTSpice

This is the LTSpice model of the Fairchild 2N7002 NMOS transistor. ...
154 views

### Best way to model noise in Current-to-Voltage Signal Amplifier Circuit

I'm working on a photomultiplier circuit shown below. When the photomultipliers are active, they produce a current signal, and the amplifier circuit converts that current signal into a voltage signal. ...
155 views

### LTSpice simulation :Unable to check the output values

I am new in LTSpice simulation .I have prepared the schematic of the following DC to DC buck converter design in folder i.e. C:\Program Files\LTC\LTspiceIV\Rough\ . My aim is to make a charger for a ...
1k views

### LTSpice: How to save output from multiple .op runs

So this is a somewhat complicated question... I am trying to run a .op simulation (DC operating point), using the .step command to iterate through a bunch of component values. I would like to save the ...
68 views

### Modelling transformer voltage drop in LTspice

I read that a transformer has a rated secondary voltage at a rated load current. So open-circuit voltage and any secondary voltage at different loads will be different. When modelling this in ...
2k views

### Diode emission coefficient and saturation current

I have created a Zener diode model in LTSpice, and now I am trying to simulate it with different values of the saturation current (IS), emission coefficient (N) and breakdown voltage (BV) using Spice. ...
273 views

### modelling of solar cell: offset in short-circuit current

I am trying to simulate the IV curve of a solar cell in reverse and forward bias. I have used bishop equation that you can see in the following picture. The mathermatical model is in good accordance ...
270 views

### Simple Interconnect circuit to simulate crosstalk in ltspice

I want to implement a very simple interconnect circuit to simulate crosstalk in ltspice because I am new to this area of crosstalk. Where can I find such a design? I have searched in the net but all ...
1k views

### Importing a verilog-a compact model in ltspice

I have a Verilog-A compact model, and would like to import it in LTSpice. I tried to google this, but to no avail unfortunately. Can anyone tell me how to do this if possible? By the way, in spectre ...
581 views

### Resonant circuit using LTSpice

I'm a college student and I was supposed to draw the Bode-plot of the following resonant circuit. I obtained this. My questions are: shouldn't I have obtained a bell-shaped curve? How can I find the ...
137 views

### What is wrong with this LTspiceIV model of a Deliyannis bandpass filter

I'm trying to analyze a Deliyannis bandpass filter at fc=7.15Mhz. I have constructed the following in LTspiceIV: which results in the following net list: ...
138 views

### boost and flyback converter

I am currently analysing this circuit But I ran into some problem since the boost component standalone raises the voltage to 40v the flyback is suppose to bring up the voltage to a further 540v ...
347 views

### Convergence problem in pspice but not in ltspice

I am trying to simulate a circuit in LTSPICE and it simulates without any convergence problems. However when I copy the netlist into pspice and try it simulate it I get strange results. It keeps ...
722 views

### LTSpice missing an SSR Component?

I want to simulate some circuits with SSR component but LTSpice does not provide this. From Eagle and KiCad I learned I can create my own component diagram. I'm not sure if I can do this also with a ...
373 views

### Spice code for uplim and dnlim?

Does anyone know where I can get sources for LTspice's uplim and dnlim? I'm trying to port a netlist from LTspice to ngspice. ...
22 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 ...
42 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 ...
20 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 ...
24 views

### How can I force LTspice to redraw a plot during a long simulation?

Sometimes during long simulations, the LTspice plot window will display a yellow "broken" icon, and/or simply not render parts or all of the data. Sometimes the axis are missing, sometimes it only ...
35 views

### How to simulate memristor crossbar array in spice properly?

I am trying to simulate a memristor crossbar array. But I found the readout voltage is constant for 3x3 and 5x5. Theoretically, the readout voltage should decrease with crossbar size. I check the ...
49 views

### Auto-numbering components in LTspice

I'd like to re-number the components of my LTspice simulation from left to right and top to bottom to make the schematic more presentable. For example, in the circuit below, I'd like R44 to be R1, R50 ...
41 views

### Infinite Negative Magnitude in LTSpice

I am trying to make a current Dependent current source LTspice and I finally got it to compile, only to get a magnitude of -1.#INFdB on my readout. The dependent sources on this program are very ...
94 views

### Low output voltage on buck converter

I am making use of the LM2678 adjustable version switching regulator in the design of a 5.5V buck converter. I made use of the design equations detailed here: lm2678 datasheet For the following ...
77 views

### How to do switching noise analysis of dcdc on LTSpice

Background : In one of my board i have used LT8471 as DCDC , as my cards being analog cards, i tried maximum to seperate the power network and analog chain from noise, my initial problems with dc-dc ...
61 views

### LTSpice LTM4622 test fixture “ignoring empty pin current” error

When I run .tran .5m startup for the LTM4622 the simulation runs properly , but I get the error shown below. I'm wondering whether I should worry about it, since the simulation results line up with ...