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.

Filter by
Sorted by
Tagged with
2
votes
2answers
24 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=...
-2
votes
0answers
38 views

SPICE simulation - No Oscillation Frequency detected [on hold]

I have simulated an Oscillator using SPICE. When I write the command to determine steady state error, the ELDO command returns- No Oscillation Frequency detected. What is the possible solution of it?
0
votes
1answer
45 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, ...
-1
votes
1answer
44 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
votes
0answers
51 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 ...
0
votes
0answers
38 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). ...
2
votes
3answers
59 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 ...
0
votes
0answers
84 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 ...
1
vote
2answers
50 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 ...
0
votes
4answers
114 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 ...
0
votes
1answer
34 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 ...
1
vote
0answers
40 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
vote
2answers
123 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
votes
1answer
41 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
votes
1answer
87 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 ...
0
votes
1answer
25 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
vote
1answer
32 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 ...
4
votes
3answers
269 views

LTSpice: how to setup sinusoidal or exponential voltage source?

My textbook proposes to calculate power for the voltage source which has sinusoidal or exponential waveform. Probably my question is very silly, but I really don't know how to input textbook's ...
0
votes
1answer
176 views

Problem driving IPB065N15N3G MOSFET with HCPL-316J driver

I want to drive an IPB065N15N3G MOSFET. I am making a boost converter. The driver I am using is the HCPL-316J (a combined optocoupler and driver). Below is a picture of my schematic. Please tell me ...
0
votes
1answer
25 views

Gain with inversing Op Amp on Equalizer

I know I posted a question about this circuit before, but I'm running into a problem. I know this is a terrible equalizer design but I'm trying to learn to put in use what I learnt with Op Amps and ...
0
votes
1answer
37 views

Ltspice Full-wave rectified signal issue

I have done a simple simulation with Ltspice with a bridge diode rectifier as shown with the picture below. However I have observed an issue in the shape of the output voltage and not the current ...
0
votes
0answers
24 views

How can I simulate “definitions” (DEF/ENDDEF) and to draw (DRAW/ENDDRAW) on LTspice, is it possible?

I have the circuit XR2211 described on "definition" with the commands DEF and ENDDEF, and drawn with the command DRAW and ENDDRAW. Working simulations in LTspice there are many information, but this ...
0
votes
0answers
61 views

Gate driver circuit stuck

I am trying to design a gate driver for mosfet using HCPL-316J in LTspice. Schematic .zip file. In the zip file the name of schematic is "Main_schematic". Other two are libraries for the components ...
0
votes
1answer
80 views

Audio Equalizer LTSpice Simulation

First, I'd like to say i'm not experienced on circuits, but i'm doing my best to learn. I'm trying to create an audio equalizer which is capable of amplifying low frequencies (20Hz-200Hz), mid ...
2
votes
1answer
41 views

LTSpice: Get linear results using .meas command

Another quirky LTSpice question. I am measuring input impedance and using a .meas directive to get the impedance at specific frequencies: .MEAS AC Zi_freq1 FIND V(in)/I(v1) AT=10k When I right ...
1
vote
1answer
93 views

LTSpice simulate log amplifier

Consider we have a nonlinear opamp circuit like this. According to theory this op amp should take log of input. I wonder whether it is possible to get a response like this : I tried to plot vOut ...
0
votes
1answer
29 views

DC DC converter simulation time slow in lt spice

Usually I can 'finagle' DC to DC converter simulations into working in a timely manner, this one has me stumped. I have done the standard gmin/abstol/reltol/cshunt combination, set initial conditions ...
0
votes
2answers
26 views

LTSpice: How to Add Trace of Two Swept Values

I'm sure there is a really simple explanation for this but I can't seem to figure it out. I am sweeping the series resistance of the source voltage and I am trying to see the transfer function output. ...
1
vote
2answers
70 views

LTSpice Sallen-Key Filter

I'm new to simulations on LTSpice with op amps (and LTSpice in general). I've been trying to simulate a Sallen-Key low pass filter and the simulation is nowhere near my calculations plotted with \$...
0
votes
1answer
59 views

How to avoid the saturation of the current amplifier?

I have to calculate current gain of the following circuit and to model it in Spice. I arbitrarily set Is = 0.0002 A: Here are the results provided by LTSpice: Also, in order to find an equation for ...
0
votes
1answer
32 views

LTSpice -Resistor value controlled by on/off Switch

Is there a way to vary my resistor R4 in picture based on if the switch is on or off? For example, if S1 is off, I want my R4 value to be 10 Ohms, and if it's on, I want my R4 to be 100 OhmS. And if ...
0
votes
1answer
93 views

Test cases for for OTA in LTSpice

Here is a component OTA provided by LTSpice which has inverting non inverting common and output node. I am in process of modelling this OTA behavior form LTSpice to PSpice. I reffered this link for ...
0
votes
1answer
46 views

Wheatstone bridge and difference op-amp

I use Wheatstone bridge as a dual voltage divider to feed both inverting and non-inverting inputs of differential op-amp: Theoretically voltage can be calculated using voltage divider expression: Va =...
0
votes
1answer
20 views

LTspice Monte Carlo with different model libraries

I'm trying to figure out how to do my first Monte Carlo analysis in LTspice. I have a very simple schematic that includes the SPICE model for PN 74LVC3G17DC (vendor link). The distribution from the ...
0
votes
0answers
37 views

Low-Speed CANbus Common-Mode Choke Insertion Loss

I'm designing a low-speed CAN transceiver breakout-board (schematic below) and I'm trying to select the proper choke to use to reduce common-mode noise. I've found a few common-mode chokes meant ...
0
votes
0answers
24 views

import touchstone file into ltspice [duplicate]

Does anyone know how to import Sparameter (touchstone) files into ltSpice and how to use them? I have downloaded s3p format file, but I don't know how to use it. I cant find any information in the ...
0
votes
1answer
71 views

How to install a scr model in ltspice

I have downloaded an scr model file from this website and pasted it in the same folder as that of my .asc file. But ltspice still shows unknown subcircuit called for the scr present. What am I doing ...
1
vote
1answer
121 views

Why does LTspice XOR gate have more than two inputs?

LTspice has the following symbol for XOR gate: But as far as I can see the XOR gate has two inputs.
0
votes
0answers
86 views

S parameters LT SPICE

I read the help section on .net and found that i can use either a node (Vout) or a resistor (I(Rout)) to specify the output node. However the 2 give me different values of S parameters for the below ...
0
votes
0answers
59 views

Frequency comparator circuit in LTspice not outputting expected state

I'm trying to simulate the circuit in the method shown here in LTspice as: I use the same parts 74HCT74 and 74HCT00. But the circuit does not function. Here I set F2>F1 and the outputs at R1 and R2 ...
0
votes
1answer
50 views

LTspice DC-blocking capacitor not working

I have been busy with a frequency shift keying modulation circuit in LTspice. The modulator works but I have this horrible DC-offset! I have tried high-pass filters and DC-blocking capacitors but I ...
1
vote
2answers
86 views

How can I get FROM and TO times of trig on measure statement of LTSPICE?

I need to measure the voltage on two signals which have a difference of phase, so in order to do the measure that I need I have to get V1 (t) and V2 (t + delay_between_signals). One way to that is by ...
0
votes
0answers
36 views

SCR triggering in LT Spice

I have been trying to trigger a SCR in my circuits but an error shows up every time. Unknown subcircuit called in xu1 n002 n001 n003 scr This is a screenshot of ...
0
votes
1answer
57 views

DC-DC converter not simulating correctly

I am trying to design a solar charge controller to charge a 12V battery, my solar panel is made of 9 cells that are 5W and 0.5V per-cell. I would like to make a booster circuit to get the voltage up ...
2
votes
1answer
74 views

How to assign the same value to multiple resistors in an LTSPICE circuit

I have around 10 resistors in a circuit, all with the default value "R". I defined the directive .param R=100 Upon running the simulation, I get the error ...
1
vote
2answers
76 views

Why is the cutoff frequency of this highpass filter with formula different from LTspice?

I used this online tool to play around and design a Sallen-Key low pass filter with a cutoff frequency of 0.3Hz. When I now put the resulting values for R1, R2, C1 and C2 in the formula I get exactly ...
1
vote
3answers
68 views

Failed to plot junction capacitance versus reverse voltage in LTspice

The 1N4001 diode's junction capacitance versus reverse voltage plot is given as follows: I guess to measure this capacitance they applied 1MHz 50mV pk-pk sine wave signal as reverse biased and varied ...
0
votes
0answers
21 views

LTspice Monte Carlo analysis vs. .meas command

I designed some analog second-order all-pass filter in LTspice and provided Monte Carlo analysis as well. I want to evaluate the obtained AC results with .meas command, particularly: Magnitude ...
1
vote
0answers
75 views

Error converting PSPICE model for LT Spice

I'm using LTspice XVII, and I'm having issues generating components from PSPICE component files. Previously, I was able to follow the method of opening the netlist file, highlighting the name, right ...
1
vote
4answers
64 views

LTspice - analyze current with varying resistance

I would like to graph current from V1 over varying resistance instead of voltage. Is there a way to do this?