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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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. ...
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1answer
503 views

How to design a SPICE model from data sheet?

I am new to SPICE simulation and I am looking for spice model file of LTC 1065 data sheet can be found here here. I searched a lot on Google but I could not find ...
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830 views

LTspice: Noise simulation AND AC analysis in one plot

Is it possible to run a noise simulation and an AC simulation independently from one another and display the results in the same plot? Or better, is there a way to determine the SNR in one single ...
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IR2110 LTspice simulation weird behaviour

I am obtaining weird voltage behaviour at the gate of my high side mosfet controlled by IR2110 which is controlled by PWM. PWM configuration: Vinitial = 0 Von = 5v Tdelay = 0 Trise = 7u Tfall = 7u ...
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Viewing netlist on native ltspice for mac

I have a mac os x 10.9.3 and I run the native ltspice on it. I cannot seem to access the netlist (the text file version of the schematic) on it. Looking at the website: http://www....
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Are the stock transistor models in LTspice accurate at RF?

Just checking, I'm doing some experimenting of small signal RF design in LTspice.
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807 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 ...
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663 views

How to plot the frequency response of transconductance of BJT with LTSpice

I need to plot the frequency response of the transconductance of this circuit in the picture with LTSpice but I don't know how. Can you please help me urgently how should I do it? Thanks
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224 views

Problem simulating a fixed transconductor with LTSpice

I am simulating a fixed transconductor circuit with LTSpice. When I apply \$1\$V for input voltage, (for DC Sweep) the voltage of collector of \$Q_1\$ has good amplitude (\$30\$mV to \$330\$mV) while ...
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623 views

How reliable or trustworthy are LTSPICE demo circuits?

I'm looking at a few switching power supplies and one of the demo .asc files for the particular controller I was looking at really seems to fit my requirements. Can I use their schematics in designs ...
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823 views

Pseudo-Nmos inverter in LTSPICE

In LTSPICE, I've built a pseudo-NMOS inverter and I've got 2 tasks to do using it. 1) I've a initial guess for Wn value of NMOS. I start the simulation with this value however, I need to optimize it ...
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867 views

Creating an adjustable output regulator, in LTspice

Firstly, I'm having some trouble with simulating a variable resistor in LTspice.. I am wondering if this can be done? Also, does anyone have any advice on how to theoretically analyse this circuit? I ...
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Designing a Filter

I am trying to design a filter which has the following Bode plot, So according to this site I designed the filter as shown below, As the two cross over frequencies are f1 = 50 Hz and f2 = 200 Hz, I ...
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Cross-conducting half-bridge

I attached an LTspice schematic, a very simplified version of a MOSFET half-bridge driven by a push-pull isolated signal transformer. The FETs are cross-conducting, but their gate pulses are not ...
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330 views

Current sink - work in simulator, doesn't work in real

I've built current sink to drive wheatstone bridge. I've counted that I must reach current ~0.2mA to properly working whole measure system. Picture below present my current sink (I use MCP6001 op amp):...
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983 views

LTspice earthing information

In my simulation I require Earth on my chassis so that filter could be simulated. But I am not getting how to make an Earth in LTspice. Please note: This question is regarding ' LTspice ' ...
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1answer
567 views

Where is the text for the symbol stored in LTspice?

The following is an image of the symbol opamp.asy. I opened the same file using Notepad++ and have pasted the contents below: <...
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2k views

A good reference for modeling pmos transistors in LTspice?

I've been trying to learn how to use LTspice, and I'm attempting to create a model for a pFET I've been using/will use on a real board. However, since my specific transistor isn't already in LTspice'...
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1answer
1k views

Modeling transformer in Ltspice

I am trying to model a transformer of 1:100 ration in Ltspice, here is the picture of it The above circuit is stepping up the input voltage by 100 times but I see something strange which is when I ...
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LTSpice - Printing resultant parameters based on expressions

I'm designing a circuit but I'm computing the values of components based on a set of design values. For example, ...
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3answers
427 views

Voltage dip on MOSFET switchable current shunt

I have the following circuit built up in LTSpice which will be used to switch in different sense resistors for current measurements. The mAEn signal switches the M1 transistor on at t=10ms which ...
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1answer
3k views

How to model IR LED Diode in SPICE [duplicate]

How does one model an IR diode in SPICE? Specifically, the TIL38. Datasheet here: http://www.supermoduul.com/PDF/TIL38.pdf I get it that Is needs to be found - ...
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1answer
17k views

Simulating SMPS with ideal switch in LTSpice?

Yes, this in a portion of a homework assignment (hence the idealized and slightly asinine problem statement). Aside from solving the circuit (which I have done), I am supposed to simulate the ...
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462 views

How to fit MAX941 macromodel to LTSpice “opamp2”?

I am new to adding models to LTSpice. I have successfully added OPA350 from TI, but with MAX941 from Maxim Integrated I get some errors due to the LTSpice "opamp2" model does not have the same amount ...
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1answer
2k views

Syntax error in LTspice

I researched online and came across a code given here for PWM source in LTSPICE. When I save this .asc and try to open the same, I get the following error: Aborting: Unknown schematic syntax: ...
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463 views

LTSpice simulation trouble

I'm simulating a passband amplifier (some 80 - 200 MHz) stage with two transistors. I'm using LTSpice. When I simulate the transfer function I get a maximum gain at a given frequency, let's say 100 ...
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622 views

spice representation for mechanical problems

As a mechanical engineer, for my work, I need to compute some displacements which are represented as a summation of frequency dependent admittances on a structural system and I would like to use this ...
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2k views

Digital simulation display

I am new in the field of electronic circuit simulation and the two articles i am reading from http://en.wikipedia.org/wiki/Electronic_circuit_simulation http://en.wikipedia.org/wiki/SPICE have led ...
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134 views

Why does this parallel->series rewrite change my AC simulation results a little?

Here are two circuits I've simulated. Both have a current source of \$\sin(\omega t)\$ mA with \$\omega=1000\$. They should be equivalent but give different simulation results. Here are the simulated ...
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1answer
3k views

How to draw an impedance in LTSpice?

I can draw a resistance or conductance in LTSpice, but how can I draw an impedance component? I've seen them drawn as unfilled rectangles before. I've tried searching the component list for "impedance"...
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LTspice: when I turn a schematic into a subcircuit it behaves differently. Why?

I'm trying to model a low frequency LED flasher based on a BEAM Pummer (basically a pair of CMOS inverters wired as an oscillator, plus a charge pump) in LTspice. I have the base flasher circuit ...
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1answer
1k views

LTSpice: Silicon diode substitution improves Schottky clamp simulation

I'm simulating this circuit in LTSpice: The input is a 1 Mhz square wave with 10 ns rise and fall times. Plotted are the input, output as well as transistor base voltage. Now here is what happens if ...
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15k views

Why is my simple boost converter giving me such a high peak output voltage?

I am trying to understand switch-mode power supply fundamentals through a simulation in LTSpice. I wanted to build an excruciatingly simple boost converter circuit following a teaching model often ...
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1answer
348 views

Measured VS Ltspice Difference in P-Chan JFET Attenuator

The following circuit is a slow switching +-15V audio signal attenuator: Why are the measured voltages (shown in white boxes) so different from the SPICE values (shown in the graph)? Note that ...
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442 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. ...
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1answer
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SPICE Model For Voltage Reference

Anyone aware where can I find SPICE models for MAX6126, MAX6250 etc? I searched a lot and could not find. If anyone knows, can you please share the link/file?
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1answer
2k views

Why is the output from this astable 555 the reverse of it's simulation?

The simulator in LTSpice looked OK ... so I moved to the breadboard with an LED (eventually replaced the LED with a buzzer) at pin 3. One more difference in the assembled circuit is the condenser at ...
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1answer
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Choosing a ground for ltspice circuit

I am just getting into this software. I construct my circuit, and it tells me to choose a ground. I only have experience with "ideal" circuits and circuit elements, and have only seen "ground" in the ...
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3answers
2k views

Does LTSpice support a “Remainder” or “Modulus” function?

I am trying to change a parameter in LT Spice with if statements and make it change on whether a different value is even or odd. Mathematically, this would be easy with a remainder or modulous ...
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Unijunction transistor in LTspice?

I would like to simulate a simple oscillating circuit involving an unijunction transistor. I do not find such component in LTspice so I figure I need to import one. Could please show me step by step ...
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1answer
607 views

Can I simulate any component with LTSpice?

I'm trying to build a very basic 3.3V supply, but would like to simulate the circuit in LTSPice if possible, before I physically build the circuit. I'm using a couple of components not found in ...
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1answer
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Simulating real world transformer with LTSpice

I'm studying LTSpice, and I'm playing in transformer simulation. I want to modelize a real world power line transformer in a reasonable way: I mean I don't need an exact simulation of some specific ...
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1answer
3k views

Voltage regulators in SPICE software

I am having trouble figuring out how to add voltage regulators to my circuit for SPICE simulation. The regulator is a 78L10AC voltage regulator, 10V, 5% output tolerance, LP package. I have most of my ...
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1answer
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DC power supply simulation trouble

I'm trying to simulate a relatively simple AC->DC power supply in LTSpice, but it's not quite cooperating with me. I've followed this schematic: only replacing potentiometers with resistors due to my ...
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1answer
4k views

How to correctly simulate a simple LM2907 circuit in LTSpice?

I'm trying to convert the frequency of a 0-5V square wave, which ranges from 0-20kHz, to a voltage using a simple LM2907 (8 pin) circuit. Using R1 as 100k, I've calculated C1 to be 416pF for a ...
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1answer
1k views

Simulating Multiple Feedback Low Pass filter using LTSPICE

I am trying to simulate the follwoing circuit in LTSpice IV. What I am looking for is overall performance in frequency domain. I downloaded and readed a lot of LTSpice guides, but none of them were ...
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How does the Arduino Deumilanove Auto-Reset Function work?

I'd like to hear some explanations as to how the Arduino Duemilanove resets the ATMega328P over USB through the FTDI FT232R transceiver. I know it involves the IDE playing some games with the DTR ...