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 a very liberal license, it is lightweight, and isn't crippled in any way.

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LTspice: Troubleshooting a common emitter amplifier

This is a screenshot of a common emitter amplifier my instructor made in LTspice (everything is working fine): This is my attempt to make the same circuit (it isn't working, there's no amplification ...
haifisch123's user avatar
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25 views

How to get deadtime loss from LTSpice?

I am doing phase leg simulation. Anyone know how to obtain deadtime loss from LTspice? And what is the formula for deadtime loss? Deadtime applied here is 100ns. Thanks.
User691's user avatar
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How do I use ideal MOSFET model in LTspice? or How do I set voltage in node without voltage source?

I want to simulate the principle of 1T1C DRAM cell. But if I model voltage source in Bit line, bit-line voltage is set by its input signal. So I want to seperate bit line, using ideal MOSFET component,...
Jungwan Noh's user avatar
3 votes
1 answer
103 views

LTspice: How can I plot the derivative of a function?

In the given circuit I plotted I(R1) with respect to time and tried to plot it's derivative using d(I(R1)). However d(I(R1)) doesn't look like the derivative of I(R1), so I'm wondering what went ...
haifisch123's user avatar
5 votes
2 answers
640 views

What is this circuit? (FM detector?) - LTspice

I have this circuit from college (almost 15 years ago) that is through-hole components wired together and it picked up the strongest local radio station. I now can't get it to work, so I'm wondering ...
tlab's user avatar
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1 answer
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How to interpret Ids of low-side FET in phase leg configuration?

I am simulating a phase leg configuration as shown below using a GS66508T GaN FET. Does anyone know if the circuit is working correctly according to the current plot? There is current spike above 30 A....
User691's user avatar
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0 votes
3 answers
82 views

LTspice problem - AND gate gives wrong output - please help

I am building an SRAM memory in LTspice. For the input I am using two muxes in column. Inside the muxes I have a problem with one of the AND gates- please see attached picture- the lower and gate is ...
nizan m's user avatar
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32 views

Effect of coupling factor in flyback converter relative to rectifying diode

I'm simulating a CCM flyback converter on ltspice, and I need some help in understanding the results when I decreased the coupling factor from 1 to 0.96. When K=1, the voltage appearing across the ...
Hamza Harbi's user avatar
0 votes
1 answer
74 views

How Does This Diode Affect This Circuit? [closed]

I am learning about electrical engineering and have a question about this circuit. I don't have a very niche question, I'm just wondering how the circuit is affected by the addition of the LED. You ...
Sqidy P's user avatar
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2 answers
127 views

Generating a clear sinusoidal wave through the oscillator to generate the "Ding Dong" sound

I am working on a project to try to recreate a close replica of the "Ding Dong" doorbell sound. I have yet to make the decay. (I would definitely appreciate if you have tips for that.) I am ...
user369928's user avatar
3 votes
1 answer
63 views

Voltage drop issues in LTspice simulation for buck converter using SW model

I have a LTspice design issue where I encounter the same problem, even when I use other available simulations. Whenever I increase the load, there is a significant drop in voltage, despite having ...
chami's user avatar
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2 votes
1 answer
80 views

OPA656 Simulation works on TINA but not on LTspice

As mentioned in the title I use LTspice as my main workflow to simulate circuits. One of my circuits is using an OPA656 amplifier. I attach a picture of a simple schematic I made to test the issue. It ...
Victor's user avatar
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2 votes
2 answers
120 views

Why do the diodes make a huge difference in an RC sinewave generator circuit?

In the following LTspice simulation of a sine wave generator circuit, it cannot oscillate without D1 and D2, but as long as D1 and D2 are added, (1+R5/R6)=1.5 can also oscillate (as shown in the ...
谢一鸣's user avatar
1 vote
2 answers
79 views

LM317-N output voltage lower than expected in LTspice Simulation

I am designing a circuit that requires a regulated 1.75 V source. After searching around I found the LM317-N voltage regulator and got it's SPICE model from TI to simulate it within my circuit. The ...
Jayson Okhman's user avatar
1 vote
1 answer
62 views

OpAmp Offset Null Pins in LTSpice

I'm simulating the following circuit, where the Op Amp is an LM741: The LM741 is an 8-pin device, and this design calls for using 7 of them. From the datasheet, here are the pin connections: I have ...
Dan's user avatar
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0 answers
41 views

Cannot get the required simulation waveform of a Quasi-z source inverter using Si mosfet

This is the circuit I'm trying to replicate, with the waveform. I found it here. This is my attempt at it, but the waveform does not match. Update: This is the waveform I got, how to get it without ...
ADNAN KHASGEER's user avatar
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How to solve the LTspice error "Questionable use of curly braces in xxx."?

When I set up the following circuit, I ran into a question about the use of braces({}) The following are error messages: Why can't the first V be recognized by LTspice, or is something else wrong?
wxss's user avatar
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0 answers
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Extracting equation/formula of drain current for the circuit model

I have simulated this circuit model in LTspice. Now I want to do an experimental fit for the graph for transient analysis of Id. Can anyone help me solving this circuit for Id? Or give me an ...
Samiha Tahsin's user avatar
0 votes
0 answers
46 views

Could not open include file "amplifier.sub"

I don't understand why this file that include my subcircuit can't open be included.
France Issenmann's user avatar
0 votes
1 answer
60 views

Slow simulation speed of a Very High frequency circuit (LTspice)

I've been working on optimizing the simulation time for a larger circuit. Before asking for assistance, I experimented with several approaches: Adjusting simulation settings, such as altering ...
Harry Larkin's user avatar
3 votes
2 answers
112 views

Using a N-channel JFET as a current source

I have used the BF256 (N-channel JFET) many times as a current source, but it is a through hole component and I prefer to use SMD. I found a few documents on the internet that all list other dynasaurs ...
hennep's user avatar
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3 votes
1 answer
79 views

Quadruple MOSFET charge pump simulation does not work as expected

Background Source claims that this MOSFET-based charge pump circuit should work. The schematic looks logical and I was able to reason my way through its expected behaviour. I tried simulating the ...
pfabri's user avatar
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2 votes
4 answers
543 views

Why doesn't my OP Amp comparator work in LTSpice? (AD8665)

When V2 > V1, Vout should output approx. 5.3V. When V2 < V1, Vout should be approx. 0V. But this op amp seems to always output 5.3V regardless what V2 is. What could be going on here? Is this ...
BobaJFET's user avatar
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How do I understand the reason behind the incorrect result in below LTspice simulation?

Shown below is the LTspice simulation for a full bridge rectifier. The simulation shows 'wrong' result for open load condition (Rload =1 GΩ). Ideally it should be same as other 2 cases. Why is the ...
Dynamic_equilibrium's user avatar
0 votes
1 answer
47 views

I could not manage to use Switch Component in LTspice

There is a circuit to control a pwm signal with a switch in Ltspice. But it does not switch of despite to off mode of controller voltage. Is there anyone to give me some suggestion. My and gate ...
Mr.JuniorEngineer's user avatar
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0 answers
24 views

OnSemi NCV1076 Ltspice Model Lib

I am trying to desing a SMPS with LTSpice. There is a driver which ı can use in real. It is NCV1076. But ı could not find a .Lib Model to use in LTSpice. There is a simulation model but it is only for ...
Mr.JuniorEngineer's user avatar
1 vote
1 answer
68 views

LTspice: SEPIC simulated output voltage does not match known output voltage

I am designing a SEPIC that meets the following criteria: ➢ Vin = 15 V-35 V ➢ Vout = 25 V ➢ Output voltage ripple 1% peak to peak ➢ Switching frequency 100 kHz ➢ Load 10 W-50 W Calculations have been ...
eutectic_codswallop's user avatar
0 votes
3 answers
55 views

What causes this LTspice error message?

LTspice error message: Voltage source VSS and voltage source VDD are paralleled making an over-defined circuit matrix. You will need to correct the circuit or add some series resistance. Paralleled ...
Batuhan Yılmaz's user avatar
0 votes
1 answer
52 views

LTspice - RF LPF design insert loss shows -6 dB

I am trying to simulate an LPF in LTspice, but the insertion loss shows up as -6 dB while I expect the value to be close to 0. Am I setting the simulation up wrong?
Aryia's user avatar
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0 votes
3 answers
85 views

Problem Using Resistors in LTSpice

I am new to electrical engineering and I’m having a lot of issues with resistance in LTSpice. Because I can’t set the current, I am unable to determine how far the voltage will drop. For example, I ...
Sqidy P's user avatar
  • 13
1 vote
2 answers
82 views

Building SPICE models of optocouplers

Looking through this answer about the 6N137 optocoupler I wonder where one can get all those paramaters like Is, Rs, N, various internal resistances, etc. that are used to simulate the optocoupler. I ...
LevGor's user avatar
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0 votes
2 answers
63 views

Simulation of high side N-channel MOSFET with Bootstrap in LTspice

The inverter circuit I made from N-channel MOSFETs is given below. I used bootstrap for the high sides. Bootstrap capacitors are C3 and C1. The gate voltage of the MOSFET is working properly, the ...
Mhan's user avatar
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0 votes
0 answers
18 views

How can I get the value of pole capacitor and zero resistor in LT1575's open_loop ac analyze

I want to ask the LT1575. Is this my circle connection problem? Why the C4, C3,and Rz can not affect the phase margin in open-loop analyze. Improved image: -
sh Wan's user avatar
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3 votes
1 answer
155 views

How can I draw LC resonant circuit frequency response in LTspice?

I would like to create a frequency response graph of an LC resonant circuit, illustrating the attenuation (in dB) versus frequency. The generated response seems inaccurate. It begins at 10 MHz and ...
Atrahasis's user avatar
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1 vote
1 answer
48 views

LTspice custom component - error when placing multiple

I'm having issues with a circuit I'm trying to build using analog multiplier AD633. I downloaded the model from the official site. I included it in the schematic using the guide provided by LTspice: I ...
Giuseppe La Spina's user avatar
1 vote
0 answers
23 views

How are SPICE files created compared to S4P files generated from a VNA?

When measuring impedance versus frequency using the same data in both SPICE and S4P formats, why do I obtain different results? COMMON MODE IMPEDANCE Common mode impedance 10514 Ohm at 79.1 MHz S4P ...
Alaska's user avatar
  • 101
1 vote
1 answer
34 views

LTspice parameters

I want to know how the .mod/.lib files in Ltspice are created by manufacturers. Let's say we have a Common Mode Choke (CMC). It will have some parameters as per its equivalent model at different freq ...
Andr7's user avatar
  • 263
4 votes
3 answers
353 views

How to check for slope of a square wave output in LTspice

I want know if there is a certain formula that needs to be used to get the positive and negative slope of a square wave. Let Vn001 be the indication if its positive and negative? Or can I simply trust ...
jaxillrplusone's user avatar
0 votes
0 answers
75 views

Positive and Negative Dual Power Supply

I want to build a dual power supply board that works with 12V DC from the power adapter and gives +/-15V at its output. I came across a schematic in LT3094 datasheet on pg 30. I am trying to simulate ...
courageouslywin's user avatar
3 votes
1 answer
64 views

In LTspice, is there any way I can obtain the frequency response of power converter alone?

I am aware of the following methods. But my intention is to understand the behavior of power converter alone, before adding the controller and feedback loop. FRA analysis: Provides the open loop ...
Dynamic_equilibrium's user avatar
1 vote
1 answer
73 views

Slow simulation on LTspice

What could be the reason for the slow simulation speed for this converter circuit I have emulated from Fig 9-5: https://www.ti.com/lit/ds/symlink/lm5145.pdf?ts=1710376974553
Andr7's user avatar
  • 263
0 votes
2 answers
91 views

Voltage-dependent current source in LTspice

I am trying to model a voltage-dependent current source. The current has the following dependence: I = A + B*exp(voltage/C), where A, B and C are constants and exp is the exponential function. The ...
RDS's user avatar
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1 vote
4 answers
82 views

LTspice: triangle wave circuit not producing any waveform

I've implemented this circuit in LTspice from this Triangle Wave Generator tutorial. Unfortunately, when I run the simulation, it doesn't produce a wave at all, just a flat VDC output. Any help would ...
Abstract's user avatar
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1 vote
1 answer
65 views

LTspice - simulation of SPWM is giving unexpected result

I am trying to make SPWM with op-amps. I also made a simple NOT gate with a simple transistor. The first op-amp is working well when its output is not connected. When I directly connect the first op-...
Mhan's user avatar
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1 vote
1 answer
50 views

LTspice repeating arb voltage (BV) block

I am trying to generate a rectified sinewave with a "flat" DC top. I managed to generate 1 cycle (shown). I used an arb voltage (BV) block, now I just need to get this to repeat, for x ...
Phil's user avatar
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1 vote
1 answer
50 views

NanoVNA measurements of attenuation do not match simulation results

I am measuring RF Tap in Pi configuration using NanoVNA (see attached picture for test setup). If I terminate RF Path output with 50ohm resistor and measure attenuation between RF Path input and RF ...
andrzej's user avatar
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2 votes
0 answers
134 views

Simulation of transimpedance amplifier in LTspice

I am trying to simulate a circuit that is presented in a research paper by Dr Behzad Razavi. I am using LTspice for the simulation (please see the attached image and netlist for the circuit). I am ...
Masood Salik's user avatar
1 vote
0 answers
68 views

Why my Common mode choke with 2 turns showing multiple Peaks in the graph?

I analyzed the CMC choke by Wurth Electronics (part no: 744830039080) using VNA and obtained the insertion loss for both common mode and differential mode. The graphs match with the datasheet: While ...
Alaska's user avatar
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3 votes
2 answers
168 views

LTspice Meas Directive?

I need some help with LTspice MEAS directive. I have a simple circuit, a DC power supply, and a variable Load resistor to observe the current limiter behavior. I made the variable load resistor and ...
Dereck's user avatar
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0 votes
1 answer
50 views

LTspice Bode plot filter analysis

I am designing a π-type LC filter with a frequency cutoff of approximately 1khz. Simulating the filter in LTspice gives the following Bode plot. It starts dropping off at ~100hz before dropping ...
lemon's user avatar
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