Import spice model in Proteus and draw JFET drain curve

Proteus is an excellent electronics circuit simulation and PCB design software. Sometimes we need to simulate circuit with components which are not available in proteus. In this tutorial we will show how you can easily import spice model for a component easily and quickly perform simulation with the component. This method is easier and quicker than creating a new component. For this tutorial we will use a JFET transistor 2N5457 transistor. We will import spice model for 2N5457 and drain its drain characteristic curve.

The following video shows how to import spice model in Proteus and draw JFET drain curve.


Step 1

The first step is to find and download spice or pspice model for your component. In this case we want to create 2N5457 JFET transistor model which is not present in proteus. After searching for spice model for 2N5457 transistor no ready made spice model for 2N5457 was found. Instead we have found the following spice model description.

.MODEL J2N5457 NJF(Beta=0.150m Betatce=-500m Rd=1 Rs=1
+ Lambda=2.3m Vto=-2.572 Vtotc=-2.5m Is=181.3f Isr=1.747p
+ N=1 Nr=2 Xti=3 Alpha=2.543u Vk=152.2 Cgd=4p M=311.4m
+ Pb=500m Fc=500m Cgs=4.627p Kf=1.045e-002f Af=1)

You may find your component spice model ready to download in .cir, .lib or .mod format. If you don't find already downloadable spice model file you can also utilize spice description as above. You just need to write the above spice code into some text editor and save it with some name and with .lib extension. So here what you need to do is to copy the above spice model description and paste into a text editor. Then you need to save the file with some name like J2N5457 with .lib extension. So the model file will be J2N5457.lib.

 2n5457 spice model

You should save the file in some directory of your project or in the proteus library folder. The following picture shows the J2N5457.lib file inside tutorial directory.

Import spice model in Proteus


Step 2

This step explains how to create simulation component and how to Import PSpice models into Proteus. Open proteus, search for JFET and then click on modelling primitives. Then click on the NJFET to select it. This is as shown below.

Import spice model in Proteus

Place the NJFET component in the schematic editor and double click its properties. In the properties window, for the Spice Model field enter J2N5457 as indicated in the spice file(see above) and for the Spice Model File field browse and select the the J2N5457.lib model file that we have created and saved earlier.This is as shown below.

import JFET transistor spice model in proteus

 Now the 2N5457 JFET component is ready to be simulated.

Step 3

In this step we will perform simulation to test the 2N5457 JFET component that we created. For simulation purpose we will draw the drain curve characteristics in proteus. 

From the generators panel we select two dc sources for Vgs and Vds and apply them on the gate and drain terminal of the JFET. We will ground the source terminal. Then we will use current probe from the probe panel, rotate it downwards and attach to the drain terminal of the JFET. This is illustrated below.

draw JFET drain curve in proteus

To obtain the drain characteristic curves, we select the transfer graph from the graphs palette and place it onto the schematic editor. Right click on the graph and select Add Traces. Then in the Add Transient Trace window select from Id for the Probe P1 field and click OK. This is shown below.

draw JFET drain curve in proteus

Next double click the graph to open the properties window. In the properties window, select Vds in the Source 1 field and Vgs in the Source 2 field. Also change the change the stop value for Source 1 Vds to 25 and stop value for Source 2 Vgs to -1. Click OK to exit.

proteus JFET model transfer graph


To run the simulation click on the SPACE key on your keyboard or right click on the graph and click on Stimulate Graph. 

draw JFET drain curve in proteus

You should obtain drain curve characteristics of 2N5457 JFET transistor in proteus graph as shown below.

jfet drain curve in proteus

To open the graph in full window you have to click on the edge of the graph. The following shows the drain curve characteristics of the spice model for the 2N5457 JFET transistor.

2n5457 drain graph in proteus

 So in this way you can easily import spice model of a transistor in Proteus and quickly simulate the transistor instead of creating a new component with spice model.

Once you have a working transistor component with spice model you can create and simulate circuits. Following are some example tutorials of using JFET transistor in Proteus.

- How to design JFET source follower?

- How to design Common Gate JFET Amplifier 

- How to design common source JFET Amplifier

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