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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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1answer
21 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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0answers
71 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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0answers
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
30 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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22 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 ...
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1answer
64 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
38 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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0answers
26 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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20 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
73 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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0answers
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
65 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
34 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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31 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 ...
0
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1answer
48 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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0answers
33 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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55 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
83 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
58 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
61 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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0answers
29 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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0answers
25 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
67 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
34 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
149 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
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1answer
32 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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0answers
56 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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2answers
122 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 ...
2
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1answer
105 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 ...
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1answer
90 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 ...
0
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1answer
40 views

Pulse frequency modulation mode in buck converter MAX15062

I am modelling MAX15062 DC-DC buck converter using datasheet in PSpice, initially i worked on control loop. This buck converter has two modes PWM and PFM mode. With MODE pin unconnected works on PFM ...
0
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1answer
52 views

LTSpice error with the V() function in a subcircuit

I'm trying to do a simulation with a subcircuit, and I've narrowed down the issue to the V() function. The simulation fails with the message 'can't find definition of model "V" ' Here is the spice ...
5
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3answers
844 views

LT Spice Voltage Output

I am using LT Spice for simulation of my circuit. I have used a probe to check for the voltage on the Capacitor. What is the green dotted line that can be seen in the plot? Thank you.
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1answer
672 views

How do I import a spice model into LT spice?

I decided to create a question of how to import models into LT spice since there were questions that are related but no definitive guide on how to import 3rd party models on this site. There are many ...
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0answers
29 views

Constant current limit in the SIMPLIS

I wanted to convert this error amplifier form Pspice to SIMPLIS, for now i am using voltage controlled current source (VSCS) with the FB nod to the negative and Vref to the positive node of the device ...
0
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3answers
136 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 ...
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1answer
113 views

Simulation on LTSpice

LTSpice does not have a gap sensor as a component. Is there anyway I can either download a gap sensor or is there a way to create my own one.
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0answers
29 views

2:4 Decoder on LTSpice [duplicate]

LTSpice does not have a decoder component so I have had to make my own using two inverters and four AND gates. I am not sure if I have done it correctly.
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0answers
12 views

Simulation of decoders on LTSpice [duplicate]

I need to simulate a 2:4 decoder on LTSpice however the component does not exist. Does anyone know of a way to simulate it?
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0answers
82 views

Simulation of decoder on LTSpice

I need to simulate a 2:4 decoder on LTSpice however I can not find the component anywhere. Does anyone know of a way I can simulate it?
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0answers
92 views

opamp constant-gm bias circuit

I try to incorporate the constant-gm bias circuit (Figure 6 in Improvements_in_biasing_and_compensation_of_CMOS_opamp) into the PFC (positive feedback frequency compensation) opamp, but it resulted in ...
2
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2answers
797 views

If Manufacturer spice model and Datasheet give different values which should I use?

I'm trying to simulate an LED circuit but I am getting a large difference in results from the simulation vs calculations done using the datasheet information. In this case both the spice model and ...
2
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1answer
94 views

NTC Project (Wheatstone Bridge + Instrumentation Amplifier) - Stuck!

I've been lurking through these forums for years but just now had the urge to ask for help. I'm creating a thermometer (using an NTC thermistor) for my college project. I began to analyze my sensor ...
2
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1answer
41 views

Is a circuit simulation package available with models from multiple vendors?

I need to simulate a filter that will be used with a DAC. I need to model noise, accuracy, and drift to calculate ENOB and identify tradeoffs. I have used LTSpice for my modeling needs for the last 10 ...
1
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2answers
115 views

If I need to find an MOSFET spice model with a particular length and width, where do I start?

I was using a 180nm NMOS and PMOS but now need to use an NMOS with about L=.36u and W=100u. I have two models but I dont think I can just change the length and width to any value. How can I check if ...
1
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2answers
169 views

SPICE BJT simulation results

I'm trying to simulate simple BJT circuits to verify my hand calculations. Following is my circuit, I'm just trying to get the calculated DC collector current with the shown voltages and parameters. ...
4
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3answers
1k views

Strange opamp's output impedance in spice

I'm simulating this circuit in Micro-Cap, which is the clipping stage of a guitar effect. The opamp model is the "NE-5532" I want to measure the input and the output impedance. I expected an output ...
0
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1answer
99 views

Voltage Multiplier Problem

I´m working on a voltage multiplier with 5 stage, i´m using the same capacitor and i think that my problem is the current load but i actually think that with a resistor in the output of the multiplier ...
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0answers
34 views

spectre save command - usage

I did look at save command documentation in Spectre user and reference guide. But it still looks confusing to me. I am specifically looking for commands to do following two task: 1) probe all nodes ...
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0answers
152 views

Transient Noise Analysis in HSPICE using Monte Carlo simulation while preserving process variation

I want to analyze the effect of noise on a simple transistor circuit using HSPICE, while maintaining process variation. The basic setup is as follows: The HSPICE models for the transistors are ...