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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Why is my LTspice simulation so different from my calculation by hand?
This is the circuit:
$$V_{in} g_{m1} + \frac{V_{in}} {r_{o1}} = (V_{in} - V_o) s C - \frac{V_o} {r_{o2}}$$
$$\Rightarrow \frac{V_o} {V_{in}} = \frac{s C - g_{m1} - 1/ r_{o1}} {s C + 1/r_{o2}}$$
The ...
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Coil current discharge on a resistor in a simple circuit
Attached is a picture with the circuit in LTspice.
There is a 5 volt pulse voltage source. Parallel to the voltage source I connected a coil and a resistor.
Why don't I see the high voltage on the ...
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2
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No DC offset observed in the CE amplifier circuit part
The objective is to make an audio amplifier. We have decided to make one that has four stages: a pre-amp with a gain of around 120, the next one is a CE amplifier with a gain of around 5, the third ...
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LTspice 24 `.ini` file location
Background
LTspiceXVII had a well-defined location for its .ini file.
LTspice17 (i.e. the successor to XVII) stores its .ini ...
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Operational amplifier question in LTspice
I was asked to pick values for the resistors (I picked R2 = 78 Ω and R1 = 2 Ω) and for Vminus and Vplus.
Can someone please explain what these voltage sources are for and what values I should give ...
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What is the point of analysis and biasing calculations when real world performance is going to be much lower in analog circuits? [closed]
I am making a 3-stage audio amplifier as a course project. The first stage is a differential amplifier, the second stage is a common-emitter amplifier, following that there is a passive filter and ...
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1
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61
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Simulation time for Full bridge
This is a full bridge circuit which I am trying to simulate in Ltspice with a snubber. When I use ideal switches instead of MOSFETS, the simulation works fine. But when I use the real mosfet models, ...
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CML Latch simulation in LTSpice
I am trying to simulate a CML Latch in LTSpice (schematic below), but the simulation results do not seem right. I am using N_50n transistors from BSIM4 model. L = 60n for all transistors, W = 10u for ...
2
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2
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Clipping of output waveforms in a push-pull amplifier circuit with op-amps, how to fix?
I don't know what the circuit is called; I found it in the suggested schematics of a Resolver to Digital Converter IC.
The circuit is an amplifier circuit that has two push-pull amplifiers and a bunch ...
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Transformer Model LTspice - Flyback Voltage Clamped on Primary but Still Present on Secondary Side
I'm simulating a circuit in LTspice using a pulse transformer to drive a JFET gate. The circuit is supposed to work as follows: We drive M1 (N channel FET) to pulse current from a 20V source through a ...
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2
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LTspice: weird behavior of simple RC circuit
I try to model a simple RC circuit with input of 2 A DC and I get an out voltage (Vc) of 2 TV. I am not sure what I am doing wrong.
EDIT:
This is for MacOS
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Instrumentation amplifier using folded cascode op-amp is not working
I made the sizing for a folded cascode operational amplifier, which is working well, however when I am trying to implement an instrumentation amplifier in LTspice using the blocks, it does not amplify ...
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Why won't this differential amplifier work without these two additional resistors?
I'm trying to measure a differential voltage in LTSpice using the following structure:
The simulation results are correct, the voltage at the output is very similar to the differential input voltage. ...
2
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1
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How to simulate a 30 inch FR-4 lossy channel (20dB loss) using ltline symbol in LtSpice?
For designing a high speed serdes system, I need to model a lossy channel of FR-4 substrate of length as 30 inch and 20dB attenuation. How can I implement it in LtSpice tool?
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How can we drive an 8 ohm speaker if it can only support around 1.5-2 watts for an Audio Amplifier Circuit?
Goal of the circuit:
Must be able to deliver 1.5 W to the speaker (8 Ω) at 1 kHz.
First Problem
1.) how can we drive an 8 ohm speaker if it can only support around 1.5-2 watts? Because when we input ...
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1
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Circuit Simplification of (Series/parallel sources)
The question asks to find $$I_s \space\space and \space\space I_x$$
However, before doing so, I should simplify the circuit. Is my simplification correct?
(I.e. is tripling the value of I_s and ...
5
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1
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What causes these spikes in an LTspice circuit analysis of a full adder?
For the following full adder circuit:
I get the following output for s (I have the same problem with COUT):
The graph itself is correct, but those spikes should not be there. I know that I have to ...
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0
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Op-amp circuit and simulation
I solved the following circuit (by which I mean finding the output voltage) and I tried simulating it to check my results. This is the main circuit, without the op-amp power supply connected:
And ...
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0
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Having trouble simulating a two-stage differential amplifier in LTspice
The following is an LTspice simulation for a two-stage differential amplifier.
The simulation takes hours. What am I doing wrong?
Spice netlist:
...
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0
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80
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MOSFET parasitic turn-on
I'm simulating a circuit which uses a high-voltage SiC N-channel FET to discharge a large voltage (something close to the breakdown voltage of the FET, 1.7 kV). The power supply for the circuit is a 1 ...
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2
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simulation output impedance of ADA4522-1
I have been trying to simulate the output impedance of ADA4522-1 using LTSpice. I have added a sinusoidal voltage source with 1Vp-p voltage at 1MHz at the output and connected the input to ground ...
2
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1
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How would I create an analog block function in LTSpice?
I'm trying to create a small-signal model of a PSFB converter in LTSpice. The blocks in red are what I am trying to create, essentially a multiplier block which computes various .PARAM parameters that ...
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0
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How do you fix this 'unlabeled value' error?
I'm really new at this and I can't understand what value is not labeled here.
3
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75
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How do I configure a negative clamper in LTspice?
I am trying to make a negative clamper in LTspice. The pulse source goes from 10V to -10V harmonically. My aim is to lower it's voltage by 7.3V, so it will have a pulse graph going from 2.7 to -17.3V, ...
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2
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106
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Bizarre behavior with SIN LTSpice
I have this circuit I'm supposed to analyze. I am asked to set v1 to a sine wave V1= A sin (2pi f t) with a frequency f = 1 kHz and A = 5mV. I think I did everything right, but when I run the ...
4
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1
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342
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LTspice: simulating temperature
I want to simulate the effect of temperature on a semiconductor.
I can use .temp ... or .option temp ... or ...
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2
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How can I draw these circuits in LTspice?
I am new to electronic circuits and I don't know how to draw these circuits. I can draw some basic closed circuits but I never understood these open ones. Would really appreciate if someone can help ...
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How do I properly import a .lib description into a LTspice symbol?
I am trying to simulate the TI part TPS62808 in LTspice, Pspice for TI, and Tina TI. I managed to easily run the simulation in the latter two simulators, but the models were specifically made for them,...
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1
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79
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Differential output resistance with LTSpice
I have a simple NMOS FET where I would like to plot the differential output resistance at the operating point of Vgs = 1.7V (which is the Vgs voltage for Id=9.4mA)
I managed to plot the output ...
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0
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LTspice Simulations with PCB parameter Tamb = 75 C vs on-board MOSFET working at 75 C comparisons
I have built up LTspice simulation model for DC2786A. I want to have the self heating effects of the MOSFETs and check how the efficiency of the converter is affected. But for the junction temperature ...
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0
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LM27762 voltage regulator LTspice simulation error
LM27762 datasheet
I imported the latest model from the Design tools & simulation for the component.
I used the following layout from the datasheet as reference, capacitor values as defined in ...
2
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1
answer
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LTspice exception: Time step is too small in flip flop simulation
I have scheme with simple JK-trigger with Reset and Preset:
But, I have error:
Time step too small; initial timepoint; trouble with and-instance A7
(it can say any AND gate) when try to start ...
3
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2
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Wrong LTspice simulation results when circuit has a large common mode potential to ground node
I'm trying to simulate the effects of a common mode signal on an optically isolated analog input circuit. I was seeing terrible common mode rejection ratios no matter what changes I made, and ...
2
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1
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LTspice model file for new component
I would like to add some new components to the LTspice library. I have never done this before.
The online SPICE forum discusses 3rd party component steps. It says I have to download the SPICE model ...
3
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1
answer
119
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Need regulated 15 kV output
I was just playing around with this ZVS circuit I made in LTspice. It was made to output 15 kV, but when I saw its actual output it had spikes of 25 kV, then it stabilized after a while. How to ...
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1
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70
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Floating node of amplifier in LTSpice
I have been trying to create an actively loaded degenerated CS amplifier with current mirror in LTSpice and whilst working on other aspects of the amplifier the Vout node decided it was floating. I'm ...
2
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1
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How can I add an LM567 in LTspice? [duplicate]
From searching the web it seems it is not included with the installation of LTspice, so I will have to add it as a 3rd-party model.
I am fairly new to LTspice and I'm not sure how to do this as I ...
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2
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LTspice IV: Stability of op-amp circuits
I am studying the stability of op-amp circuits using LTspice with the help of this video. I can see many threads on Stack Exchange like this one, but the explanation is not clear to me.
I have a ...
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122
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LTspice - auto-transformer impedance ratio
Can you please clarify what formula is used by LTspice to calculate the auto-transformer impedance transfer ratio for the equivalent circuits below?
Both circuits resonate on the same frequency. I ...
3
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1
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Failed to simulate active current mirror in LTspice
The following is my schematic for active current mirror:
This is a SPICE simulation for my old question:
The following is the \$V_{out}\$ plot.
What's wrong with my \$V_{out}\$?
The asc file is ...
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1
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LTspice inrush current simulation
I'm trying to simulate the inrush current of a system that I measured with an oscilloscope before.
In my simulation I have a voltage bouncing effect on the wire between the supply and the Rshunt that ...
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1
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204
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Creating third order butterworth filter with Sallen–Key topology
I am trying to design a third order Butterworth filter with Sallen–Key topology. I am quite new to this and there is not much only about third order variations.I have the following requirements:
Gain:...
0
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0
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LTspice induction motor model
I'm trying to simulate the dynamic model for induction motor in (alpha, beta) stator axis.
Results are not correct but I don't know how to fix this issue. How can I fix them?
Code:
...
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DC-DC converter possible by using Zener breakdown as input to transistor gate?
Suppose you have a DC voltage source that is higher than required, in this example let's assume one wants a 12V voltage source from a 18V source. Would it be possible to have a circuit, where the ...
3
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2
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LTspice showing wrong voltage
I am trying to get this circuit to work correctly. I am following a book, and according to Ohm's law this resistor should be 350 Ω to get 2 V at the LED. I am only seeing around 800 mV.
To get around ...
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1
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How can I use the external library for the 2EDF7175F Gate Driver by Infineon in LTSpice?
I want to simulate a circuit including the Infineon 2EDF7175F (Gate Driver) in LTSpice 17.
This is my circuit:
I created both the irfl024z (Mosfet) and the 2EDF7175F by opening the .lib in LTSpice ...
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1
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LTspice simulation
The Zener diode is an LM385-BZ 2.5. I could not find that SPICE model, so the circuit is running on standard values.
The first picture below with Vout = 0-3.3 V is what I am trying to get, but the ...
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2
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Impulse response ltspice
Is any one able to explain why I am not getting an impulse response when I probe across L1? The voltage shown seems to be the same no matter where I probe on the circuit.
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VOM617AT SPICE model not working
I downloaded the VOM617AT (optocoupler) SPICE model from the following address:
https://www.mouser.com/ProductDetail/Vishay-Semiconductors/VOM617AT?qs=9vrc9xEJKyxW%252B%2FlvaQ%252BSPg%3D%3D
I am not ...
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1
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CD4007-based subthreshold MOS amplifier
I'm considering buying a pair of CD4007 ICs so that I might build a subthreshold NMOS amplifier.
I've seen it discussed here.
I'd like to build this circuit depicting a simple subthreshold amplifier.
...