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
0
votes
2answers
214 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 ...
0
votes
0answers
37 views

How does a high pass filter and a low pass filter work for an amp?

I'm researching how to incorporate treble and bass into an amp. X1 is for bass, X2 is for treble and X3 is for volume. Intuitively, for me, if a high pass filter only allows frequency above a ...
0
votes
1answer
28 views

Defining Wavefrom as an expression in LTSpice

Is there a way to define a variable as a function of other nodes in LTSpice so that I can later plot it? For example V(OUT) = (V+) - (V-) And then I can plot V(OUT) without having to do the math ...
6
votes
2answers
175 views

Help figuring out what is the limiting factor on the noise level in this analog optocoupler circuit

I am trying to build a circuit that takes a {-10V ... +10V} analog signal and outputs the same {-10V ... +10V} voltage but galvanically isolated from the input. The idea is similar to that of digital ...
1
vote
1answer
42 views

Non inverting op-amp gain LTspice?

This configuration of OPA134 in LTspice has have a gain of 1.5 and hence should have a voltage output of 3. However it does not. Why? Spec: http://www.ti.com/lit/gpn/opa4134 Spice model: http://www....
0
votes
1answer
167 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 ...
2
votes
1answer
174 views

Dead-time in Full Bridge Inverter (LTSpice Simulation)

I am trying to generate a dead time between two switching legs in the conventional full bridge inverter. However, by simply including the delay block for one pair of switches - just shifts the signal ...
2
votes
1answer
280 views

LTSPICE - Simulation Portability

Does anyone know of a comprehensive source of information on LTSPICE directories, libraries, the Control Panel - Sym & Lib Search, model locations, etc. as they relate to simulation portability? ...
1
vote
2answers
84 views

Could someone answer my questions on a transformer with regulator circuit in LTspice?

The circuit itself is a UK mains power supply turning 230Vac to 20Vdc. The first section is a transformer. The second part is a bridge rectifier, it then moves onto a voltage regulator by the name of ...
0
votes
2answers
67 views

LTSpice .Step (2nd dimension) Syntax Error

I am currently attempting to use the step function to simplify/increase portability of some of work circuits. Can't share the exact circuit, however I am simply attempting to define a variable/s, use ...
0
votes
0answers
24 views

could not open library file ltspice

first of all, I am not using a third party component but a component from the LTspice library. after updating the software, whenever I select any diode, it shows me the error and could not run. i ...
0
votes
1answer
45 views

How to model a one-port (reflection) measurement in SPICE?

I have the equivalent circuit for an antenna and I would like to use SPICE to simulate the \$S_{11}\$ (reflection coefficient) response. I know how to simulate two-port measurements (like shown here),...
2
votes
1answer
130 views

Power amplifier simulation and real time experiment mismatch problem

Thanks in advance to anyone who will take the time to read my first post here. At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a ...
0
votes
0answers
37 views

Construct SPDT switch in LTspice

I construct exactly SPDT switch symbol as detailed in the above titled procedure, up to "save as" the new symbol. I received error message; Symbol spdt incorrectly defined.Dublicate pin number :5. ...
4
votes
1answer
291 views

How can I export the frequency response from LTSPICE without phase wrapping?

After I plotted the frequency response of a circuit using LTSpice as shown: I exported the plots data as a .txt file in order to plot them after that using MATLAB, however, after I plotted the data ...
0
votes
1answer
90 views

Analog Switch cannot provide 0V output when OFF

I'm trying to simulate in LTSPICE the following simple circuit, and I cannot get 0V output when the analog switch is open. Can anyone please explain why?
-1
votes
1answer
188 views

Can .param change based on time?

I am looking for an option to change the .param value dynamically during transient analysis. Is it possible ? For example, .param delvto = 300m from 1ns to 10ns .param delvto = 120m from 10.1ns to ...
1
vote
1answer
33 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: ...
0
votes
1answer
76 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 ...
0
votes
1answer
33 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
0
votes
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?
1
vote
3answers
185 views

Is there a way to embed/group initial value and switch combinations in LTspice?

I have a circuit with several ICs and components. But the circuit will behave differently depending on the inputs or the switches set. Each time to simulate a combination I have to delete/modify ...
2
votes
4answers
48 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 ...
1
vote
2answers
58 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 ...
5
votes
1answer
1k 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 ...
4
votes
1answer
875 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 = ...
1
vote
1answer
52 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 ...
0
votes
1answer
154 views

LTSpice error with V() function, … when referencing net within a subckt (V(subCktName.NetName))

I've converted an IBIS model to a SPICE model using microCap, and am trying to simulate that subckt with LTSpice. Using LTspice, I get an error with the subckt in the library. "u1:g1: Unknown ...
4
votes
2answers
533 views

Meaning of unevenly spaced data points in LTspice

When View --> Mark Data Points is selected on the waveform, LTspice shows data points unevenly separated along the time axis. Does anyone know what do these points correspond to? It doesn't look like ...
4
votes
2answers
334 views

DC input on op amp integrator

I am trying to integrate a DC tension with a classic op amp integrator. The problem is : when I simulate my circuit on LT Spice, the output will always be equal to the VEE tension of the op amp ...
8
votes
3answers
310 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 ...
1
vote
1answer
174 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 ...
0
votes
3answers
163 views

Sine Wave Input for Op Amp Integrator but Output Looks Weird

The input is in sine form (AC input) but the output (in blue color) is the straight line. So what is wrong with my schematic in LT Spice this time? I thought I should've got output in sine form if I ...
0
votes
1answer
53 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
votes
1answer
59 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 ...
2
votes
1answer
77 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 ...
1
vote
1answer
96 views

Isolated three level pwm LTSPICE

I am doing a simulation on LTSpice of a three level ANPC. The ground is connected to the neutral point (i.e in the middle point of the DC input) and the gate drivers are isolated by using a DC DC ...
1
vote
2answers
127 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 ...
0
votes
1answer
61 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 ...
-2
votes
1answer
87 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. ...
0
votes
1answer
219 views

LTspice gain enhancement sallen and key highpass simulation

I have been trying to simulated a filter and amplification circuit. In one of the stages I am using a LP Sallen and Key circuit and another I am using a HP Sallen and Key circuit. I can successfully ...
5
votes
1answer
181 views

Bireciprocal lattice wave digital filter

I am trying to model a bireciprocal Cauer filter in LTspice but I don't get the expected results. More precisely, using \$\gamma = \frac{re(p_i)-1}{re(p_i)+1} \$ where \$re(p_i)\$ is the realpart of ...
0
votes
0answers
28 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 ...
1
vote
4answers
914 views

Waveform generation with opamp

I need to design a circuit that generates the voltage waveform shown in the Figure 1 when an input voltage is applied as shown in Figure 2. Figure 1 and Figure 2 are in the second link below. Only ...
1
vote
1answer
70 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 ...
0
votes
2answers
167 views

Model of Mosfet Switching in LTspice

I would like to perform a simulation on LTspice about a switching MOSFETs. In particular on how the parasitic inductance and capacitance affect the switching transient. In order to perform this ...
0
votes
1answer
379 views

LTspice error reading a downloaded model

I'm downloading a model for an n-channel MOSFET, the DMG6968U-7. This is the SPICE code: ...
2
votes
2answers
920 views

Export error log values from LTspice

I have used .meas expressions to calculate harmonic values in LTSpice. The problem is that these are now in the error log and I cannot export them. Is there a way to export error log values in a .csv ...
0
votes
1answer
47 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 ...
0
votes
1answer
220 views

Power over time for RC ish circuit in LT spice

I have a simple circuit in spice that I put a 0-5V step function into. So basically as square-wave going in. Then I can get my current and voltage waveforms out, or do some math to get power. But I ...