Questions tagged [spice]

A famous textual circuit simulator with a number of graphic front-ends. Please tag with the precise flavor used (e.g. Pspice, LTspice, ngspice, Multisim, Proteus, Qucs) whenever appropriate (e.g. syntax or debugging) because there are substantive differences between implementations.

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SPICE model for Current PWM Controller

Is it possible if we run AC analysis using general current PMW controller & not the actual PWM controller specified by the vendor? Reason is because I asked the chip maker regarding their SPICE ...
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3answers
50 views

Netlist for symmetrical component

Is there any difference between the following two netlists for a resistor connected between node5 and node0 with resistance 20K ohms? • R1 5 0 20k • R1 0 5 20k If not, is a resistor the only type ...
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65 views

Nodal analysis for resistive circuit

Given the following circuit: I know that I1 = I2 + I3, but what would be the relationship between I2,I3,I4, and I5? I would assume if there are 5 unknowns, we'd ...
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27 views

How do I alter a subcircuit in SPICE?

I am passing in environment variables to my spice circuit, so that I can script things in bash and plot in gnuplot, avoiding the cumbersome flow control built into spice. ...
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1answer
87 views

Why won't this low pass filter work in spice?

I just started working with spice and I feel like I'm making some sort of obvious mistake but unsure what. This works fine: ...
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2answers
50 views

Why does LTspice resistor noise disappear when setting value with .param?

When performing a noise analysis in LTspice of a 1kΩ resistor, a noise level of 4nV/rtHz is simulated. However, if this resistor value is set to 1kΩ using .param, ...
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ltspice: assign list of values to .param

If I want to do a simulation for a set of .param values I can do .step param R1 1k 10k 1k. But this generates a set of ...
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1answer
39 views

SPICE IC model in-circuit power dissipation

I'm looking into a way to calculate the power dissipation of any arbitrary IC in circuit on SPICE. I eventually hope to create simple scripts that can list power dissipation of the device and ...
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31 views

How do SPICE simulators differ?

I've used about 3 or 4 spice simulators over the years and I'm wondering if the simulations for more complicated circuits would be comparable. Do some handle certain circuits better than others? Or is ...
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2answers
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Equivalent circuit of a non-ideal resistor

I've come across two different equivalent circuits for a non-ideal resistor and I'd like to understand which is correct. The first is: and the second: These are different equivalent circuits with ...
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25 views

How to experimentally calculate transconductance of an OTA?

How can I experimentally calculate the transconductance of an Operational Transconductance Amplifier given that I know the value of bias current ?
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56 views

How to calculate total harmonic distortion in PSpice?

How can I calculate the total harmonic distortion of a sinusoidal Oscillator in Pspice? I am using eldo and ezwave for the simulations and waveforms.
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31 views

Loop Compensation Design Case Study

I am understanding loop compensation to DC-DC voltage mode buck converter from this case study Compensation Case study For example: I am simulating in PSpice Dominant Pole Compensation (Pg No 8 to ...
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uniform, bimodal and skewed distribution functions in pspice

As you probably know, for statistical analysis in pspice there are four distribution functions: uniform, bimodal, skewed and gaussian distribution functions. For typical parts such as resistors and ...
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1answer
56 views

KiCad Simulation VSOURCE Triangle waveform

I want to simulate a second order active low-pass filter in KiCad, using the internal spice-based simulation tool. The input signal must be a triangle waveform of 30kHz and 0,5 V peak to peak, and the ...
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32 views

how to pause/stop spice simulation in Altium Designer?

I am trying to simulate a circuit with Altium Designer. My simulation takes very long time, and I need to tweak the circuit frequently. Although I am able to stop/pause on-going simulation in LTSpice ...
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42 views

Understanding SPICE code in Chan Transformer in LTSpice

Taken from here: http://ltwiki.org/?title=Transformers I am having trouble understanding how the Chan core is actually linking in with the coils. Does anyone understand what the SPICE code is doing ...
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2answers
67 views

Overlay plots from PSpice - SIMetrix or SIMetrix to PSpice

I wanted to verify the accuracy of a identical model which I modelled, between PSpice and SIMetrix simulator I ran model in Pspice and SIMetrix separately and probed required nets (net names are ...
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2answers
32 views

Is power draw always modeled in Op-Amp SPICE models?

I know op-amp models are simplified versions of the actual op-amp, is it safe to say that the power/current draw is nearly always modeled?
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89 views

How to find Cpi ( in hybrid pi model) of transistor from SPICE parameters

I have the following SPICE parameters for an NPN ...
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Are there MOS VLSI Process Design Kits (SPICE models) for free SPICE simulators?

I want to do some proof-of-concept work in IC analogue IC design. I know that plenty of free circuit simulators exist (LTSpce, NgSpice etc.), however they are meant for PCB simulation and most perform ...
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1answer
40 views

Why are my net names not corectly exported to a SPICE netlist?

I have a schematic: When I export this with the "Export Netlist" feature... The SPICE netlist has renamed my Hello and World ...
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1answer
53 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),...
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40 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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77 views

representation of electrical circuits (paper)

I'm looking for an old paper about a format for representation of electrical circuits using text, similar to some of the current netlist formats. Here is what I remember: it was written by Richard ...
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27 views

References for writing spice model code?

I'm currently looking into building my own spice models from datasheet specs to ensure accuracy. Are there any references for this sort of thing? I've looked around online and haven't found anything ...
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1answer
34 views

Can we calculate the total harmonic distortion of an oscillator directly from ezwave?

Can we calculate the total harmonic distortion of an oscillator directly from ezwave? If yes, then please tell how to calculate it. Else what are the approaches to calculate THD of an oscillator.
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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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67 views

Unknown equation in the SPICE resistor model

I was looking for simple resistor spice model, and came across this: ...
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1answer
92 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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29 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 ...
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27 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 ...
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1answer
88 views

Current controlled switch with negative current?

I am trying to create a current controlled switch, which opens only at negative current, I tried this approach: ...
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33 views

Phase noise and spectrum of oscillator in SPICE

How can I plot the phase noise and Frequency spectrum of an Oscillator using SPICE.
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1answer
181 views

Delay implementation in PSpice

1.I have been using oscillator circuit as Parametric delay block with the help of other sub blocks at the output/around. Second method is RC for the delay at the output of any circuit (ABM) or ...
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1answer
37 views

Can a spice library contain different component types?

A pretty simple question that I'm having a hard time finding the solution to on the internet. I have a spice model of a diode in parallel with a resistor that represents leakage. It is a subcircuit ...
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34 views

Do diode SPICE model parameters affect each other?

I was modifying a diode spice model to better fit the datasheet parameters (the breakdown voltage on datasheet was 85V, and the model went into breakdown at 65V). I noticed the junction capacitance ...
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1answer
51 views

In your experience, how well do NPN SPICE models replicate real DC current gain

Title, I'm currently running some simulations and noticed that my DC current is in the very rough ballpark of datasheet parameters. Is this normal or does it indicate there may be something wrong with ...
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37 views

How to implement a switch in spice? [duplicate]

I have designed a circuit where I want to give a pulse of very short duration using a switch. How can I implement it in spice.
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58 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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1answer
266 views

Constant power load SPICE model

I would like to create a SPICE model for a constant power load. I'm guessing that would involve using an equation to dynamically adjust the model's resistance based on the applied voltage. How do you ...
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2answers
96 views

Charging a capacitor in Eagle SPICE

I'm trying to learn the basics of Eagle SPICE simulation with a simple capacitor charging circuit. My netlist is as follows: ...
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1answer
170 views

Testing spice model for common mode rejection ratio?

I've been trying to create a circuit to simulate common mode rejection ratio of an op amp to test the spice model's accuracy. While I've seen online that being able to use exact resistors only a ...
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30 views

Test circuits for testing input and output capacitance of an NMOS spice model?

As the title states, I'm having trouble finding resources online for confirming the capacitances of an N-MOS spice model. If there are any resources someone could point me to to learn more or test ...
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32 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 ...
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1answer
104 views

Need help with 2 Transistor Current Limiter Circuit in LTSpice

I am new to LTSpice. I have attached a picture of my circuit below: The goal of the circuit is to provide current to the R1 until It is too high. Then the BJT will activate, shutting the FET off. ...
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1answer
48 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 ...
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1answer
302 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 ...
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1answer
69 views

Eliminate external pin in SPICE netlist

I'm working with a SPICE model of a MOSFET that provides a fourth pin for setting the device temperature (driving the pin with a voltage in simulation sets the temperature). However, I don't plan on ...
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69 views

Altium Designer 19 mixed simulation

I'm trying to plot a current vs. resistance graph using mixed simulation in Altium Designer 19.1.5. I'm having a problem creating the variables and plots which are not against time. It would be very ...

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