View source for ESim/C2/Creating-a-Device-Model/English

'''Creating a Device Model'''

'''Author: Gloria N '''

'''Keywords: eSim, Device model,  KiCad, Eeschema, Simulation, Analysis, Knee voltage, Forward characteristics, Forward current, schematic, Ngspice netlist'''


{| border="1"
|-
| style="color:#000000;" | '''Visual cue'''
| style="color:#000000;" | '''Narration'''
|-
||   '''Show Slide:'''

Opening Slide
||   Welcome to the spoken tutorial on '''Creating a Device Model '''in '''eSim'''.
|-
||   '''Show Slide:'''

Learning Objectives
||   In this tutorial, using '''eSim'' we will learn -

* To create a '''Germanium Diode''' from an existing '''Device Model'''  and
* To edit a current '''Device Model'''.

|-
||   '''Show Slide:'''

Systems Requirements
||   To record this tutorial, we will use-
* '''Ubuntu Linux OS '''16.04 
* '''eSim '''version 2.0

|-
||   '''Show Slide:'''

Prerequisites
||   To practice this tutorial,
*To create a circuit schematic and simulate the netlist file in '''eSim'''.

If not, watch the prerequisite '''eSim''' tutorials on this website.

|-
||   '''Show Slide:'''

Device Models
||   The device model file begins with a dot model statement.
*'''mname''' indicates the model name like '''diode''' model '''1N4007''', '''1N4148'''.
*'''Component type''' indicates the type of model used. 

For example: '''D''' is used for '''Diode''', '''M''' for '''MOSFET''', and  '''NPN''' or '''PNP''' for '''BJT'''.

*'''pname''' is the parameter name and
*'''pval''' is the parameter value.

|-
||   '''Show Slide:'''

Device Models in eSim
||   The model components are already added in '''eSim'''. They are referred to as '''templates'''.

The '''templates''' are in a tabular form with '''parameter''' names and values.

The '''Device Model''' libraries are used for the components present in '''eSim''' underscore '''Devices'''.

|-
||   '''System Computer:'''
Desktop icon
||  To launch '''eSim''', you need to double-click on the '''eSim''' icon on your '''Desktop'''.

|-
||   '''System Computer:'''
eSim startup window
||  I have already opened '''eSim'''.

|-
||   '''eSim Main Window:'''
Click on  '''Model Editor''' 
||  Let us now create a '''Device Model''' of a '''Germanium diode''' '''1N34A'''.


On the '''eSim''' window, click on the '''Model Editor''' button from the left toolbar.

The '''Model Editor''' tab opens.



|-
|| '''Model Editor tab:'''
Click '''New''' >> Enter '''New Model''' Name'''  as '''Germanium_Diode''' >> Click '''OK'''
||A  '''New Model''' pop up window appears.

Type the '''Model Name''' as '''Germanium''' underscore '''Diode'''. 

Click on the '''OK''' button.

|-
||'''Model Editor tab:'''
Hover the mouse on the '''Diode''', '''BJT''','''MOS''' options below.
||A list of model components appears on the left corner of the '''Model Editor''' tab.

These are the models you can choose from.

|-
||'''Model Editor tab:'''

Click on '''Diode'''.
Hover the cursor on the '''Parameter''' and '''Value''' column.
||Since we are creating a new model of a '''Diode''', Click on '''Diode'''. 

The '''diode''' model opens up in a tabular form with the '''Parameter name''' and  '''Value'''.
You can see the default values.

|-
||Show Slide:
'''Code File'''
||Let us now add the spice parameters of '''Germanium diode''''.

The parameters of '''Germanium Diode''' model '''1N34A''' can also be downloaded from the '''Code File''' section.

Download and open the file in a text editor.

Copy-paste the parameter values in the respective text box in the '''Model Editor''' window.

|-
||'''Model Editor tab:'''
Enter the values in the tabular column.

||Here I am entering the values.
To enter a value,  click on the '''value''' field.
Enter '''Rs''' as  '''7'''.
Enter  '''Cjo''' as  '''0.5e-12'''.
Enter '''N''' as '''1.3'''.
Enter '''Ibv''' as  '''0.018'''.
Enter '''tt''' as  '''144e-9'''.
Enter '''M''' as  '''0.27'''.
Enter '''Vj'''  as '''0.1'''.
Enter '''Is''' as '''2.0e-7'''.
Enter '''Bv''' as '''75'''.

The sequence of parameters may vary.

|-
||'''Model Editor tab:'''
Hover the mouse on '''ADD''' and ''''Delete''' buttons.
Click '''Save'''.

||You can also '''Add''' or '''Delete''' the parameter.

After the '''parameters''' are entered, click on the '''Save''' button in the '''Model editor''' tab.

|-
||'''eSim Main Window:'''

Click '''OK'''.

||An information pop-up window, ''''Model saved successfully''' is displayed.
Click on the '''OK''' button. 
These libraries will be saved in the '''Diode''' folder of '''deviceModelLibrary''' directory. 
If the component model was chosen as '''BJT''', then the library would be saved in the '''Transistor''' folder.
Each '''template''' chosen will be saved in their respective folders of '''deviceModelLibrary''' directory.

|-
||'''eSim Main Window:'''
||Now let us simulate the characteristics of Germanium Diode.

|-
||'''eSim Main Window:'''

Click on '''Open Project''' from the top toolbar >> Double click on  '''eSim-2.0''' >> Click on '''Examples'''>> select '''Diode_characteristics''' >> click '''Open'''.

||We will open the '''Diode characteristic''' example from the '''Examples''' folder of '''eSim'''.

On the '''eSim'''' window, click on the '''Open Project''' button from the top menu.

Locate the directory where the '''eSim''' is installed.

Double click on the '''Examples''' folder.
Scroll down and select the '''Diode'''' underscore '''characteristics'''.
Click on the '''Open''' button.

The '''Diode characteristics''' example is added to the '''eSim''' window under '''Projects'''.

|-
||'''eSim Main Window:'''
Select '''Diode_Characteristics''' under '''Projects'''>>Click on the '''Open Schematic'''>>Click '''Yes'''

||To see the schematic, select '''Diode characteristics'''.
Click on the '''Open Schematic''' button from the left toolbar.
It directs us to the '''schematic editor'''.

|-
||'''eSim Schematic editor:'''
Press '''F1''' key.

||Press '''F1''' key to zoom in the schematic.

|-
||eSim Main Window:

Select '''Diode_characteristics'''>> click on '''Convert Kicad to Ngspice'''

||Let us go back to the '''eSim''' window.

Select the '''Diode''' underscore '''characteristics'''.

Click on the '''Convert Kicad to Ngspice''' button from the left toolbar.


|-
||'''Kicad to Ngspice Converter:''
'''Analysis''' Tab >> Select '''DC'''
Enter the values.

||Select '''DC''' in the '''Analysis''' tab.

Scroll down to enter values.
Enter '''Source''' as '''V1'''.
Enter '''Start''' as '''0'''.
Enter '''Increment''' as '''0.1'''.
Enter '''Stop''' as '''2'''.

|-
||'''Kicad to Ngspice Converter:'''
Source Details Tab:
Enter '''1''' for '''DC''' source '''V1'''.

||In the '''Source Details''' tab, enter  '''value''' as '''1'''.

|-
||'''Kicad to Ngspice Converter:'''
'''Device Modeling''' Tab
Click on '''ADD'''>> Double click on '''Diode''' folder>>click on ''''Germanium_ Diode.lib''' file>> click '''Open'''.

||Skip the ''''Ngspice Model''' tab.
Click on the ''''Device Modeling''' tab, click on the '''ADD''' button.
Double-click on the '''Diode''' folder.
Select '''Germanium''' underscore '''Diode''' dot '''lib''' file.
Click on the '''Open''' button.
This adds the '''Germanium Diode''' library file from the '''Diode''' folder.

|-
||'''Kicad to Ngspice Converter:'''
Click on  '''Convert'''>>Click '''OK'''

||On the '''Kicad to Ngspice''' tab, click on the '''Convert''' button.
Click on the '''OK''' button in the '''Information''' dialog box.

|-
||'''eSim Main Window:'''
Click on '''Simulation'''.

||Now, let us simulate the '''Ngspice''' netlist.
On the '''eSim''' window, click on the '''Simulation''' button from the left toolbar.
An '''Ngspice terminal''' and '''plot''' window opens along with a '''Python plot''' window.

|-
||'''Ngspice Window:'''
Maximize the '''i(v_u1)''' ngspice plot.
Hover the mouse on '''X-axis''' to point '''voltage'''.
Hover the mouse on '''Y-axis''' to point '''current'''.
On '''Ngspice''' terminal, hover the mouse on '''.model Germanium_Diode'''.

||The plot waveforms show '''DC''' analysis of the '''Germanium Diode''' model '''1N34A'''.

This '''diode''' has a '''knee voltage''' or '''turn-on voltage''' around '''0.3'''.
The '''forward current''' is around '''1.7 milliampere'''.

Close the '''Ngspice''' plot and '''Ngspice''' terminal windows.

|-
||'''Python Plot Window:'''

Check '''In''' and '''Out''' node>> click '''Plot'''

Hover the mouse on python plots after plot.

||In the '''Python''' plot window, check the '''In''' node and '''Out''' node.
 And click on the '''Plot''' button. 
You can see the '''forward characteristics''' of the '''Germanium diode'''.
Close the '''Python''' plot window.

|-
||'''Show Slide:'''
'''Shockley Diode Equation'''

||The '''Shockley diode''' equation relates the '''diode''' current '''I''' with the '''diode''' voltage '''Vd'''.
The main '''spice''' parameters that determine the '''DC''' analysis are 
emission coefficient  ‘N’, 
saturation current  ‘Is’ and 
ohmic resistance ‘Rs’.
For an ideal diode, N is equal to 1 .
This factor mainly accounts for carrier recombination. 
eSim Main Window:

Click on  Model Editor 
Click on  EDIT >> double click on Diode folder>>click on  Germanium_Diode>> click Open

Click on N value>> enter 4.0>> click Save>>click OK

Now let us learn how to edit a  model library.

On the eSim window, click on the Model editor button from the left toolbar. 

We will edit the Germanium diode parameters.

On the Model editor tab,click on the Edit button.
Double click on the Diode folder.

Select Germanium underscore diode dot lib file.

Click on the Open button.

A tabular form of Germanium Diode parameters and its corresponding values will appear.

Let us now change the value of the parameter N .

Click on the parameter N  Value field and enter  4.

Click on the SAVE button in the Model editor tab.

In the Information dialog box, click on the OK button.

eSim Main Window:





Select Diode_characteristics>> click on Convert Kicad to Ngspice>> Click on Device  Modeling Tab





Click  on ADD>> Double click on Diode folder>>click on Germanium_ Diode.lib file>> click Open.

Let us now simulate the characteristics.

On the eSim window, select Diode underscore Characteristics.

Click on Convert Kicad to Ngspice button from the left toolbar.

Let us keep the default values for the  Analysis tab and the Source Details tab.

Skip the Ngspice Model tab. 
Click on Device  Modeling Tab.
Click on the ADD button.

Double-click on the Diode folder.
Select Germanium underscore Diode dot lib file and click on the Open button.

This step was done because we have edited the Germanium diode library file. 
eSim Main Window:
Click on Convert>>click OK
Click on Simulation.


On the Kicad to Ngspice tab, click on the Convert button.
Click on the OK button in the information dialog box.
Let us now  generate the plots.

On the eSim window, click on the Simulation button from the left toolbar.
Ngspice terminal and plots

Maximize the i(u,v1) ngspice plot.
Point the cursor on the X-axis for voltage.
Point the cursor on the Y-axis for the current.
The Ngspice terminal and plots opens along with the Python plot .

Notice a decrease in the forward characteristics.

The knee voltage is around 0.5 volts, which is similar to a Silicon diode.

The forward current is 1.1 milliampere.

Close the ngspice terminal and plots. 
Python Plot:

Check In and Out node>> click Plot


In the Python plot window, check the In and Out nodes.
Then click on the Plot button.
You can see the input and output plot.
Now close the Python plot window.
Show Slide:
Summary

Let us summarise.
In this tutorial, we learnt:
To create a Germanium Diode from an existing Device Model and
To edit a current Device Model.
Show Slide:
Forum to answer questions
https://forums.spoken-tutorial.org/
Do you have questions in this Spoken Tutorial?
Choose the minute and second where you have the question.
Explain your question briefly.
Someone from the FOSSEE team will answer them.
Please visit this site.
Show Slide:	
FOSSEE Forum
https://forums.fossee.in/
For any general or  technical questions on eSim, visit the FOSSEE forum and post your question.
Show Slide:
Circuit Simulation
https://esim.fossee.in/circuit-simulation-project
The FOSSEE team coordinates the Circuit Simulation project.
We give Certificates and Honorarium to the contributors.
For more details, please visit this site:
Show Slide:			
Lab Migration

https://esim.fossee.in/lab-migration-project
The FOSSEE team coordinates the Lab Migration project.

For more details, please visit this site.

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Acknowledgment

http://spoken-tutorial.org
Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.

For more details, visit this site.
			
Thank you slide
		
This is Gloria N  from IIT Bombay signing off.
Thank you