# Questions tagged [modeling]

This tag covers finding models for electrical and electronic components and circuits

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### How do I analyze an emitter follower with a capacitive load?

How do I analyze an emitter follower with a capacitor load? At 7 MHz, a 1 nF capacitor has impedance of 22 Ω. A simple emitter follower with a 22 Ω Re is easy to analyze: However, replace that ...
• 1,120
1 vote
16 views

### Cannot get correct output in PSpice with the Buck Converter PSpice Transient Model from TI

I obtained the LM76005-Q1 transient model from the Texas Instrument website and imported it to PSpice. The website also provides a Design Calculator software, so I basically use it to determine other ...
31 views

### Diffusion Current for Non-Linear Charge Carrier Configurations

Diffusion current in a MOSFET device can be calculated using Fick's Law per $J=-qD\frac{d \rho}{dx}$. It is often taken that the charge carrier configuration ($\rho$) across the MOSFET channel is ...
33 views

### 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 ...
1 vote
168 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 ...
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39 views

### How can a power converter small signal model predict transient behaviour during a load step which is a large signal disturbance?

I see small signal model being used to predict the Overshoot/Undershoot of output voltage due to a load step. How do we justify this approach, since the basic assumption of small signal modelling is ...
• 3,032
520 views

### 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
• 235
81 views

### Determining the current carrying capability of a hollow cylinder

How can one analyze, to some approximation, the current-carrying capability of a hollow cylinder with a diameter of 3 inches and a length of 6 inches, made from 100 μm thick copper with a resistance ...
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1 vote
95 views

### Electrical modeling of multilayer structure

If I have a construction of layers wherein the topmost layer is conductive, followed by two different insulation materials in between, and a bottom structural layer that is a partially conductive ...
• 235
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### Battery Pack discharge behaviour

i want to simulate the discharging behaviour of several battery packs/modules connected in series to simulate a discharge machine for a recycling facility. I wanted to simulate possible current/...
51 views

### How to learn about memristors as a circuit designer? [closed]

I'm trying to learn about memristors to play with it in circuit design. I think it might be more intuitive to do tests and measurements rather than reading maths formulas. The problem is that I don't ...
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1 vote
85 views

### Thermodynamics of a simple electrical conductor

I derived an expression for the time constant of the temperature of an electrical conductor and was looking for some constructive feedback. Initially there is no current flowing through the conductor ...
222 views

### An AC motor is a transformer? How?

motivation: A guy I worked with years ago (~2015) who is an EE said that "an electric motor was just another form of a transformer". I'm not an EE, so I didn't do things with transformers. ...
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300 views

### What are techniques to fix/compensate parasitic effects that occur at very high frequencies in passive electronic components on circuit level?

There are of course equivalent circuit models for modeling practical passive components using idealized elementary circuit models that reflect the parasitic effects that occur at high frequencies , ...
1 vote
157 views

### Piezo sensor at resonance - equivalent model

piezo materials are commonly modelled with the BVD model When the piezo is used as a sensor, they are commonly modelled as a current source in parallel with a capacitor because à external force ...
• 31
139 views

### Is there a way to take this buck diagram and reduce it to an AC transfer function?

I am semi-dangerous with switchers but I've never really delved into the innards of them so I'd like to ask about this TPS23750 diagram. I would like to develop a model of this feedback loop of a buck ...
• 84.6k
41 views

### What kind of model can be used to simulate over- and under voltage in a Li-Battery pack?

So far I have not much experience with modeling in the field of lithium-ion cells or batteries except equivalent circuit models (ecm)-models which I've implemented and used for simulations in Matlab/...
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187 views

### Modelling of MOSFET

I was wondering if there's a way of creating a simple MOSFET model that predicts how the following circuit behaves when voltage source V is varied. As I understand it, if MOSFET M1 is in the ...
314 views

### Improving Modeling of Thermal Noise in Radio Antennae

Background I'm attempting to write a physics simulation code, one portion of which involves the simulation of the voltage observed at a set of $N$ radio antennae immersed in some medium due to ...
93 views

### Distributed-element model of a series-RC transmission line

The equations for modelling most transmission lines can be based off the telegrapher's equations but the ones I found only account for parallel resistance with the capacitance, but I would like to ...
• 373
123 views

### JFET mismatch between mathematical model and SPICE

As a sequel of this question, I built a mathematical model for the Id current of the following (same) JFET circuit: For a simplified model, I took LAMBDA=0 and set ...
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52 views

### Build simple LTspice MOSFET model for textbook examples

I am trying to build a simple MOSFET model (very simple, no parasitic capacitance, gate leakage, ohmic contact...) using LTspice to simulate school textbook example, but I don't know how to switch ...
• 623
580 views

### Why does the frequency deviation of a FM wave have different definitions?

Source 1 defines the modulation index in the expression for FM as follows: As per the expression for frequency modulated wave, isn't the frequency deviation same as Modulation index 'M'? "The ...
• 3,032
406 views

### Why are these commercial MESFET model parameters unrecognized by LTspice?

I am trying to add a commercial GaAs FET model (ATF34143) in LTSpice XVII for simulation. The model is provided on this website (http://www.hp.woodshot.com/hprfhelp/design/SPICE/fets.htm#ATF34). ...
19 views

### What are NMOS level 1 CV equation and its main parameters?

I was asked to perform MOSFET CV modeling. I looked through some papers, but I still can't clarify what the CV model equation for a level-1 NMOS is, and I am also not sure what its main parameters are ...
1 vote
505 views

### Equation for diode saturation current in photovoltaic cell model

I've been looking for mathematical models for photovoltaic cells. Most of the references I've found use the following circuit to the model the behavior: Particularly, the diode current is modeled ...
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480 views

### Can I model a diode with higher than usual junction voltage in LTspice using the "Eg" and "Vj" parameters?

I want to model a GaN transistor and include a diode to simulate its reverse conduction above ~2 V with an adjusted diode using the following model statement: ...
• 22.4k
1 vote
267 views

### Forward diode depletion capacitance formula

Does anybody know the forward depletion capacitance formulas for diodes in spice models? Background: The capacitance of a diode in reverse direction usually is dominated by the depletion (or junction) ...
• 143
1 vote
119 views

### What is the type of material used for the casing of semiconductors?

I am trying to build some thermal models for leaded and surface-mount diodes and transistors. Below is a picture of the TO-220 outline I got from the internet. What kind of material is the black part ...
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1 vote
130 views

### Error in modelling a photovoltaic panel using Plecs software. What could be wrong?

I have a work titled MPPT P and O algorithm with a buck-boost converter. The software I am to use is Plecs. First I wanted to design a photovoltaic model in Plecs. I tried to follow an example I got ...
• 11
529 views

### Antenna model by chatGPT AI - correct or not? [closed]

I asked chatGPT about a basic simplified model of an antenna according to my conception of it (pasted is the most relevant part of two separate answers). It would look like this: ChatGPT AI ...
• 465
1 vote
131 views

### Does the method of Similitude apply in electronics and electrical engineering?

In engineering, there is a theory called Similitude, which describes how models and testing conditions must be correctly scaled in order to behave correctly and represent the real thing. The reason ...
44 views

### How to include dead times into the model of the three-phase voltage source inverter?

I have been developing a Scilab model of the three-phase voltage source inverter. I have started with the idealized model where I suppose that in each of the inverter leg one transistor can be turned ...
• 1,113
1 vote
332 views

### Question about the Verilog-A implementation of a VCO

I am learning verilog-A to model analog circuits. One of the examples given in the book is that of a voltage-controlled oscillator (VCO). The book says the following about how the VCO can be modelled (...
52 views

### MNA matrix of a vacuum tube

I've been working on a project involving a digital model of a vacuum tube. We're currently experimenting with a Wave Digital Filter approach. Now I've been reading Kurt Wegner's fascinating work and I ...
123 views

### What happens to reflections when the distance between a capacitors plates is electrically long?

I understand what happens when a transmission line is terminated with a capacitor but what about when the distance between the plates becomes electrically long? For PCB mounted capacitors I know this ...
1 vote
710 views

### How to model reverse recovery diode in LTSpice?

I wanted to update this subject as LTspice has evolved from this post: How does LTSpice model reverse recovery time? To sum up the above post answered by Ste Kulov: As Ste Kulov said, LTspice allows ...
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1 vote
692 views

### What is the meaning of a negative capacitance? - Cadence Virtuoso

What is the meaning of a negative capacitance in cadence virtuoso? Here in the following image, I just want to find the capacitance of transistors using "print-->DC operating point". Can ...
1 vote
206 views

### What is the meaning of "a" and "z" in capacitor value - Cadence Virtuoso

What is the meaning of "a" and "z" in capacitor value? Here is the image: I think "a" is angstrom, But I am not sure about it.
1 vote
269 views

### Definition of small-signal capacitances calculated by Sentaurus TCAD Mixed-Mode/AC Analysis

I'm currently working on a capacitance model which will be part of a greater compact model for a planar RFET. I use Sentaurus TCAD to generate capacitance data, which I use to understand the ...
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80 views

### Obtaining the State Space representation of a microgrid by combining the state space models of the subsystems

I am trying to obtain the state space model of the DC microgrid shown in the figure. It is made of three converters connected in parallel. Each one is modeled with a voltage source that outputs the ...
1 vote
42 views

### How can I find critical field in tsmc65 transistor parameter?

How can I find critical field in tsmc65 transistor parameters? Critical field is the field which electron velocity in transistor go into the saturation region.
1 vote
35 views

### Mapping geometric to electric parameters for a PMSM machine

I am looking at a PMSM machine described by the following equations: $$\frac{di_d}{dt} = \frac{\omega_e L_q}{L_d}i_q - \frac{R_s}{L_d}i_d + \frac{u_d}{L_d}$$ \frac{di_q}{dt} = -\frac{\omega_e (...
• 11
1 vote
1k views

### How to find (mobility*Cox) and Vth

How to find "mobility*Cox" and "threshold voltage" of NMOS in cadence virtuoso? I have performed DC analysis in schematic environment and using NMOS model parameters, I tried to ...
1 vote
54 views

### Modeling first-order dynamics of a switching converter

I have created a simple, first-order model of a switching regulator in steady state (it's basically a transformer with a loss element). Its only parameters are desired output voltage $V_o$ and ...
• 1,326
1 vote
293 views

### LTspice, modeling line driver with propagation delay (LH0063)

Question I'm trying to make a component model for the LH0063 single ended line driver in LTspice... The propagation delay is the dominant parameter for the frequency response but I'm having a hard ...
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### Question regarding state-space modeling of a simple electrical circuit

Consider the circuit in the picture, where we have a voltage source (input) $V(t)$ and a capacitor $C$. The goal is to derive a state-space model of this circuit. The circuit satisfies the ...
• 101
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527 views

### MOSFET model in LTspice with Miller Theorem

I want to make a MOSFET model in LTspice with a current source and the input capacities to see what happens in the switching process. I'm not 100% sure but I think it works. Below is the formula I ...
1 vote