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Where To Find This Example

AWR Version 14

Understanding AWR .emz Files

AWR Version 13

Understanding AWR .emz Files

Design Notes

IV Curves Generated from the new Swept Variable Capability

This project demonstrates how to use the swept variable capability by generating IV curves for a device.  This project demonstrates the original way of generating IV curves using the IVCURVE element and shows another way of generating IV curves using DC sources and swept variable blocks.  This project also shows how to manipulate measurement data in the output equations using the swept variable framework.  Finally, it demonstrates a capability for consolidating results in one window.  

Overview

In AWR-DE, it is very simple to setup a swept variable. The first step is to define an equation that the swept variable block will sweep.  This variable needs to be assigned to the appropriate model parameter.  Then a swept variable block needs to be added to the appropriate schematic.  These are found under Elements > Simulation Control.  The ID parameter will be used in the measurement dialog box to specify how to display the results.  The VarName parameter is the name of the equation previously defined.  The Values parameter is where the swept values for the variable are assigned.  These settings will be further explained in this example. 

IVTrace_IVMeter Schematic

This schematic shows one way to generate IV curves.  Since the device is a BJT, the control source is a current source and the IVCURVEI curve tracer is used.  Notice that the collector voltage and base currents are set on an even spacing. 

DC operating currents are annotated on this schematic for a single base current and collector voltage.  These current and voltage settings can be changed with the Tuner (Simulate > Tune).

IV Curves_IVMeter Graph

This graphs shows the curves generated from the IVCURVEI curve tracer.  These look like standard BJT IV curves.  This plot is generated by selecting the IVCURVE measurement.  

IV Curves_SW_Var Schematic

This schematic shows how to generate IV curves using DC sources and swept variable blocks.  For the collector of the device, there is a DC voltage source with its value set to the variable “Vc,” which has a default value of 5, set by the equation.  The swept variable block called “collector” is used to sweep the value of “Vc” which is set to the DC voltage source value.  Notice that in the Values parameter that the “stepped()” built-in equations is used to sweep the value from 0 to 8 with steps of 0.2.  For the base current of the device, there is a DC current source with is value set to the variable “Ib,” which has a default value of 1, set by the equation. The swept variable block called base is used to sweep the value of “Ib” which is set to the DC current source value.  Notice that in the Values parameter that the values are typed in as a vector.  These values could have any value the user specifies.  This example uses base currents on a non-even grid, not possible with the old way to generating IV curves.  

DC operating currents are annotated on this schematic for a single base current and collector voltage.  These current and voltage settings can be changed with the Tuner (Simulate > Tune).

IV Curves_SW_Var Graph

This graph shows the IV curves using the swept variables setup in the swept variable schematic.  The measurement settings have to be configured properly to display the IV curves.  Open up the measurement settings for this graph to see how this is done.  The measurement type is Icomp with the Harmonic Index set to 0, which is DC.  The Data Source Name specifies the appropriate schematic and the Measurement Component specifies where to measure the current for the device (the collector voltage source in this example).  The next two settings in the measurement dialog (SWPVAR.base and SWPVAR.collector) only display in the schematic because those named swept variable blocks are in the chosen schematic.  The SWPVAR.collector is set to Use for x-axis to use those swept variable values on the x-axis of the graph.  The SWPVAR.base is set to Plot all traces to produce the family of curves.  

Output Equations

The output equations block in this example is used to calculate the beta for this device form the DC values simulated.  The output equations have notes for what each equation is doing and should be self-explanatory. 

Beta graph

This graph shows the results of the output equations.  It shows the beta for the device with the set base currents on the x-axis at a chosen collector current (set in the first output equation). 

How to tune a swept variable result

When you do a swept variable simulation, the simulation will simulate all of the swept variable combinations.  The swept variable measurement settings chose how to view the data.  To see this, there are a couple things to try.

1.   For the "IV Curves Sw var" graph, open up the measurement dialog and for the SWPVAR.base, change the setting from Plot all traces to Ib =2 and select OK.  You will now see the results of only Ib = 2mA. 

2.   For the "IV Curves Sw var" graph, open up the measurement dialog and for the SWPVAR.base, change the setting from Plot all traces to Disable Sweep and select OK.  You will now see the results at one base current value.  Since the swept variable is disabled, the default value set by the Ib=1 equation is used for the current source in the simulation.   

3.   For the "IV Curves Sw var" graph, open up the measurement dialog and for the SWPVAR.base, change the setting from Plot all traces to Select with tuner and select okay.  Now open up the tuner.  You can slide the tuner to change the value used for the “Ib” swept variable.  Since all the data has already been simulated, this tuning will be instantaneous.  Notice the parameter marker update the “Ib” value used for the result.   

4.   The output equation can also have different settings.  Set the SWPVAR.base back to Plot all traces.  Then in the output equations, change the first equation (hold down ctrl and double click to open) and change the SWPVAR.collector from Vc = 5 to Select with tuner.  Then open up the tuner and move and watch the beta results change.  This changes the collector voltage where beta is calculated. 

Results Display Schematic

You can drag a graph (or layout, output equations, etc) into a schematic window.  These are different view of the original object.  Notice you can edit the output equations from here or change the graph properties.  You can also select these objects and resize or delete them in the schematic. 

To create a “Window in Window”, have the window that will be added to as the active window.  Then click on the name of the window you want to add from the project manager (select the “Proj” tab).  Drag into the active window and release, the cursor will now be a “+” sign with a box below it. Next, click and drag to draw the outline of the window.  When you release the new window will be there. 

This is a very convenient way to consolidate results into one window. 

Schematic - IVTrace_IVMeter

Schematic - IVTrace_SW_Var

Graph - Beta