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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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1answer
21 views

How to use a parametric value within PULSE voltage source in LTSpice?

I would like to use a parametric symbol for the period value of the PULSE component in LTSpice but so far I have been unsuccessful. currently my source is: ...
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1answer
17 views

How to write the transient analysis ltspice directive with a stop time and start saving data time?

How to include 0.9m start saving data in spice directive? .trans 1m
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0answers
12 views

How to use .meas statements to measure duty cycle in LTSpice [duplicate]

Would anybody be familiar with how to use .meas statements in LTSpice to measure the duty cycle of a square wave?
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1answer
21 views

NOT valid mode type SIMetrix from Netlist

I am trying to run PSpice netlist in SIMetrix .cir and it says NOT valid mode type SIMetrix from Netlist, do we have to add any command other than this.
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2answers
52 views

LTSpice Simulation - How to design pulldown with voltage supply

I am trying to simulate a circuit which should pull the supply down. Problem here is, that the supply is a not current limited and the whole voltage is dropping accross the 0.1Ohm RC of Q4 and the ...
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0answers
23 views

LTSpice module for FMMT491 NPN transistor [closed]

I am looking for LTSpice module for FMMT491 NPN transistor. I have found below one, but not able to use it as it is missing .SUBCKT Does anyone know how to use this one. Thank you. .MODEL FMMT491 ...
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0answers
48 views

SiC MOSFET SPICE model not behaving properly

I have been trying to simulate a fully controlled full bridge using SiC MOSFETs and so far haven't gettng at least expected results. So I tried to check what is happening using a single MOSFET and a ...
4
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1answer
843 views

LTSpice Zener diode bug?

I'm trying to design a circuit using a zener diode but am having issues getting it to work right. This circuit works fine and show Vout = 6.198V. However, if I swap their positions - Here, Vout = ...
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1answer
38 views

Buck converter step response

I am simulating a current step in a buck converter with a resistive load that I designed. I am measuring the response while stepping the current up from 5A to 10A and stepping the current down from ...
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4answers
39 views

LTSpice multiple load iteration

I am trying to simulate a load in two different instances. In first instance i want the load to have a constant dc value of 2A, and in the second instance PULSE(2 11 1.06 100n 100n 0.30 0.8 1). I ...
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1answer
38 views

LTSpice buck converter output voltage too high

I am designing a 311V to 48V buck converter in LTSpice using ideal components for now. I am using a 48V/311V = 15.434% duty cycle in V2 which controls S1: This is the simulation output: Below is ...
2
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1answer
66 views

My very basic voltage-controlled amplifier gives an asymmetric waveform?

I want to build a voltage-controlled amplifier. The Wikipedia pages on voltage-controlled amplifiers and voltage-controlled resistors suggested using the following approach: first I would simply build ...
2
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1answer
51 views

How to simulate a simplified model of crosstalk effect in LTspice?

How can I make simple model and simulate the crosstalk between two adjacent channels of a multiplexed DAQ inputs? I observe that in its most exaggerated form, a nearly exact duplicate of one channel ...
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1answer
48 views

Effect of drain inductance on MOSFET turn off

I have made a simple circuit in LTSpice to test MOSFET turn-off time. Inductance is changed from 1.5nH to 1.5mH in a few steps. The next picture shows gate-to-source voltage and drain-to-source ...
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1answer
60 views

Undefined Symbol in ltspice code and what is heightened Def Con? [closed]

Thank you for your inputs. I have attached the schematic. I am using third party models for simulation. The problems seems to be with some unrecognizable attribute by LTspice. ...
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0answers
22 views

How to display precise values when running operation in LTSpice on Mac

In LT Spice for mac, running a DC sweep using the .op command brings up a plotting window which appears as the following: I want to see the windows version of these operations, which provides the ...
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1answer
38 views

LTspice table function

how does a table function work in LTspice? In the LTspice library, it says, table(x,a,b,c,d,...): Interpolate a value for x based on a look up table given as a set of pairs of points. I don't really ...
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1answer
57 views

Same diodes (BAT54) from two manufacturers with different LTSpice characteristics?

Leaving the package and the resulting thermal characteristics aside, do diodes with the same name from different manufacturers have the same characteristics? I would think they should, but when ...
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1answer
39 views

Back-to-Back PMOS high power dissipation

I have created a circuit in LTspice to switch between two power sources (10s Li-Ion batteries). V1 and V3 resemble the power sources which vary from 30-42V. V2 and V3 are output pins of an µC. R3 is ...
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0answers
40 views

Control and code in LTSpice

I'm starting to use LTSpice, after having used MATLAB/SIMULINK/PLECS for a long time. I would like to do some simple feedback control (PI), without analog components (OPamps, comperators, etc). Just ...
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1answer
63 views

How to power schmitt trigger in LTspice with negative voltage?

I use CD40106 model in LTspice for schmitt trigger, but the circuit I want to simulate has -5 and 0 V levels, CD40106 only accept positive value for VDD and there is no other param to change the value ...
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3answers
271 views

What are the calculations to do in practice to estimate beforehand the noise seen on the output of this op amp circuit?

I would like help with understanding something better, but am not trained in electronics so please bear with me! I am trying to make a simple circuit to take a {-10V ... +10V} signal from a function ...
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0answers
31 views

Create a nested for loop to sweep two parameters (x,y) to calculate a function E(x,y)

So I would like to plot a 3D space of a function while sweeping two other parameters. I am sure this is not possible to plot in LTspice but is there any way to sweep two parameters while measuring a ...
2
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1answer
65 views

What is the cause for a 180 phase shift between current and voltage in LT-spice simulation

Just by clicking on the resistor, I got a display of the plot of current passing through it, marked with I(R3). In my opinion it must be in phase with the voltage across the resistor, but on the ...
0
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1answer
34 views

AC Simulation in Power supply simulators

I would like to design a boost converter using LM3481 from texas instruments. To de the job, I have selected TINA TI circuit simulator, where the average model of LM3481 is given. So I have used this ...
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1answer
38 views

Incorporating ALD1106 SPICE model in LTspice

I'm trying to incorporate a SPICE model of an NMOS IC, the ALD1106. I've used it before in class, but it's been so long that I've forgotten how to incorporate the files into LTspice in order to ...
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0answers
58 views

Capacitor Storage Circuit Having Lower Voltage Than the Simulation

I designed a circuit to store a pulse of 8 volts and duration of 40 micro seconds. When I simulated the circuit it reached 3.5 volts and discharged.The circuit and the simulation is given below; In ...
0
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1answer
37 views

Emulating transistor load graph

https://www.youtube.com/watch?v=wSm_42DIKXY I have used the above link to emulate transistor load graph ( sorry if I am not using correct term ) using LTspice. . Unfortunately it is in Greek and I am ...
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0answers
26 views

MCP1630 Spice model

Does anyone knows where I can find MCP1630 spice model ? I realy need it to complete my project and microchip does not provide the spice model of this device. On my behalf, I do not master SPICE to ...
3
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1answer
41 views

LtSpice antisymmetric sine pulse

I am trying to create a pulse voltage source in ltspice. The pulse should look like a half cycle of a sine wave however the rise and fall times should be different. I can create such pulse with the ...
1
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2answers
50 views

LTSpice PWL issue with Trigger

Perhaps someone can help me. I have a problem with the trigger function in LTSpice. I load a PWL file and add the following Syntax behind it: PWL (File.xx) Trigger V(n001)>1 LTSpice gave me an ...
0
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1answer
48 views

What is the expression for collector current (Ic) in function of CTR for optocoupler?

I'm just asking about expression for collector current (Ic) of optocoupler in function of CTR because my simulation results doesn't fit with the CTR=Ic/If equation. Simulating the part CNY17-3 with ...
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0answers
20 views

How to estimate NMOS Cds+Cdb capacitance from VDMOS Pspice/LTSpice model?

I'm designing a fly-back converter and in order to calculate the switching frequency I want to know a method or formula of how estimate the Cds+Cdb capacitance of NMOS switch using the Pspice ...
3
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2answers
101 views

Minimoog oscillator LTSpice simulation problem

I am running a simulation on the Moog Minimoog Model D oscillator in LTSpice. The circuit with the models needed is attached below. The square wave and triangular wave generation work as expected. ...
2
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2answers
35 views

Non-linear Inductor LTSpice

I am trying to implement a non-linear inductor in LTSpice and to get it to saturate. I am using the following directive between N1 and N2 as advised in the help files: L1 N1 N2 Hc=12 Br=0.2 Bs=0.4 A=...
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1answer
52 views

LTSpice - envelope detector LPF behaving like buffer

I have an issue with an LTSpice simulation and I'm not sure if the issue lies in the simulation setup or somewhere more basic. The simulation is as follows: The system is as follows: on the left, ...
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1answer
48 views

My calculation for an RC circuit are not agreeing with the LTSpice simulation

I am doing calculations for an RC circuit to create a first order low pass filter. The input is a 5V peak periodic square wave with a 10kHz frequency. The resistor is 220 Ohms and the Capacitor is ...
0
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0answers
55 views

Why does the frequency of an oscillator changes with the time duration of .TRAN command?

I have simulated an oscillator circuit using OTA in SPICE. It is a self starting oscillator. However, the frequency of oscillation does not change with the bias current but changes with the duration ...
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0answers
45 views

LTSpice .MEAS Command: Measuring Mag and Phase Data

I got a real stumper of a LTSpice question for y'all. I'm do an AC analysis to calculate input impedance by setting the input to AC 1V and then adding the trace "1 / I(v1)" (where V1 is the source). ...
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3answers
88 views

Does the LT Spice monte carlo simulation definitely output the max and min voltage for any number of simulation runs?

I have the following circuit, in which i need to calculate max and min voltages possible (considering resistor tolerance). Does running a monte carlo simulation consider the absolute max and min ...
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0answers
99 views

Problem driving MOSFET with ACPL 337J optocoupler

I want to drive a mosfet. I am using an ACPL 337J optocoupler to drive it. Here is the schematic:- But I am facing problem while driving the mosfet. The signal at gate of mosfet should be a PWM but ...
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2answers
87 views

Why is LTSpice Bode plot disagreeing with a linear plot?

Here is a picture of an amplifier that I'm simulating using LTSpice. When I insert a sine wave of 0.01 volts and 314Hz as an input, I get this: The output is taken from the collector and is ...
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4answers
122 views

Why does LT spice limits frequency domain output to 65535 data points?

Background: I ran a simulation and I am generating the S21 gain of a circuit I am working with dembedding and wanted a 100% accurate and wanted a ridiculous amount of data points and when checking my ...
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1answer
35 views

Values of components in ACPL 337J

I was going through datasheet of mosfet gate driver. I wonder why is the value of component the specified one only. On page no. 13 fig 23, why the value of resistor between pin 3 and pin 6 is 10k ohm ...
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0answers
45 views

Clapp Oscillator Oscillating Frequency Strongly Dependent on the Transistor

For temperature sensing purposes, I have been challenging myself to design a dual mode crystal oscillator operating at the frequencies 30MHz and 90MHz (fundamental tone and the third overtone, ...
1
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2answers
131 views

LTspice: Simulating a Van Der Pol Oscillator

I am trying to simulate the oscillator with an RLC circuit with the initial condition V(V1) = 0 and D(V(V1)) = 0. Since LTspice does not allow initial condition with time derivatives, I set the ...
0
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1answer
60 views

LTSpice: simulate transient voltage and current in RL-circuit

My goal is to calculate transient current and voltage in a following circuit: Also, immediately after the switch is closed, initial current is 0 and then it exponentially increases until the value ...
2
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1answer
89 views

What's wrong with this circuit built on opamps?

I have built this circuit in the LTSpice, but it refuses to simulate the operation using normal solver, but shows great results using alternate. This source says Be suspicious of circuits that need ...
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1answer
32 views

LTspice: Including Time Derivative of a Node Voltage in Initial Condition

I am trying to simulate an RLC circuit with the initial condition that V1(0)=2 and V1'(0)=0. I used D(V(V1))=0 in my spice directive, but I don't think the condition on time derivative has actually ...
1
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1answer
36 views

Fatal Error Audio equalization simulation LTSpice

I'm doing a 3s audio.wav simulation on LTSpice with the following circuit (3 band pass filters and amplifiers): In this example it's boosting the bass and attenuating the highs. It loads the first ...