Lab 0 – Introduction to AWR System Simulation

radio system design lectures

Part 1– Introduction – AWR

In this lab you will learn how to simulate using AWR’s Microwave Office.

You may download a free copy at: http://www.awrcorp.com/awr-university-program/students

AWR will give you a 6 month license for free with an approved university email, e.g. .edu.

AWR is also on all of the PC clusters in the teaching labs.

Please launch AWR 11. The initial screen may ask you to select which license you would like to use (they enable different products). Please select them all. You will then have a pop-up box to remind you that this is for educational purposes only.

You should see the following:

Schematic Creation

In this lab we will be creating a System Diagram. This can be done by ProjectAdd System DiagramNew System Diagram. You can enter a name for the schematic – try “AM Radio 1.” You should see the following:

On the lower left you will see three tabs:

  • Project – contains information on the project, including simulation outputs, graphs, etc.
  • Elements – contains information on objects that can be inserted into your schematic
  • Layout – contains information on objects related to laying out components (used for E&M simulations).

Inserting Component

To insert a component. Click on the Elements tab. If you minimize all menus you will see three types of components: Circuit Elements, System Blocks and 3D EM Elements. For System Diagrams you will use System Blocks. Expand System Blocks, then click on Math Tools. Below the System Blocks list, you will see an array of icons – these are the individual components. Your screen should look like this:

Select ADD and drag it into the schematic. You can add any component this way.

An alternative method is to click on the System Diagram window so it is active and then hit the hot key Ctrl+l. This will bring an Add System Block window. You can type the name of the block in the lower section and it will find that specific block. I have found the adder by typing in “add”:

This is typically how you will insert components as there are hundreds of components and finding specific ones under the drop-down list on the left can be difficult. If Ctrl+l doesn’t work, you can use: Draw->More Elements. It will bring up the Add System Blocks window.

AM Upconverting Modulator

Please create the following System Diagram:

The name of each block (to search for using Ctrl-l) is directly above the ID. You may access the properties by double clicking on the block. Note: I have turned off most of the visible properties to make this schematic clear. When you insert an element it will have all of the properties visible. This is OK, you just need more room to space out the component so the schematic is clear. You can edit properties directly in the visible text, i.e. I could change FRQ of TONE ID=A1 by clicking on .05GHz and typing another number.

  • TONE – creates a sinusoidal signal. Set PWR to 10dBm and FRQ on ID=A1 to .05 GHz and FRQ on ID=A6 to LO_UpDn. This is a variable we will set later.
  • SRC-R – Real source; basically is a behavioral source for many uses. Set VAL=DC, this will make its output equal to the variable DC which we will create later. Think of it as “VAL=1” means 1V output. We could also tie it to a data file and have an arbitrary waveform.
  • TP – test point. These are actually at the top tool bar as well as in the element list. They are used for probing nodes. You can change the names of the TP. In this lab I will use the names in the schematic – you can make your TP the same names if you wish.
  • ADD – this adds the inputs. You could specify more than two inputs, but two is sufficient for our needs.
  • MIXER_B2 – this is a behavioral mixer – it models the nonlinear behavior of a mixer. Since we would like it to be close to ideal for this lab, set: Conversion Mode: SUM, GCONV=-6, P1dB=100.
  • CE2R – this takes a complex signal and converts it to a real signal for plotting.

To connect elements, just place your mouse near a terminal and it will change to a spool of wire. Then click on that node and click on where you would like to connect it. A wire will automatically appear.

In System Diagrams the input/output nodes are colored:

  • White: Signal type is unset
  • Yellow: Signal is set to be real
  • Red: Signal is set to be complex

You can modify the signal type by placing your mouse over the terminal triangle and wait for it to turn to a circle. Double clicking will bring up the signal properties block. Some nodes can be set by the user; some cannot be set. For now, you do not need to worry about these setting, however you may have wondered what the colors meant. We will use these settings later in the class.

You should have completed everything except the blue text on the lower left. To create an equation for the two variables we entered (DC, LO_UpDn) go to Draw-> Add Equation. Then just click anywhere on the schematic and an editable box appears. Type DC=0 in one box and LO_UpDn=500000000 in the other. The text is black. The example above is blue because I have enabled tuning. Right click on the equation and select Properties. Then click Tune. The text is now blue and the variable is tunable in AWR. You now have a complete schematic.

AWR System Simulation

AWR is unlike most other simulators where you have to explicitly specify the simulation. In AWR it is implicit through your selection of data you wish to measure. This is explained easiest by doing an example.

Let’s plot the voltage waveforms at Sum and upMix.

Go to Project->Add Graph and select Rectangular. A graph appears. Right mouse click and select Add Measurement. You should see the following:

The Add Measurement is used to add all types of measurements. The different parameters are described below:

  • Measurement Type – this is the type of measurement. For this lab, we will be using System and System: Spectrum.
  • Measurement – this is the measurement you want. In the example above we have selected WVFM, which is a time based waveform.
  • Block Diagram – this is the schematic where we want to measure something.
  • Test Point – you will see all of the test points you added there. This is why it is a good idea to use names. Select TP.Sum
  • Time Span – since we chose WVFM this appears. Select 50 and then ns for units.
  • Complex Modifier – this is where you can specify to plot the Real, Imag., Mag. or Angle of the signal. Choose Real.

You can leave the other settings alone. Click OK. You will see a legend appear that describes the waveform that will be plotted. It is grey – this means that there is no data or that the data plotted is not up-to-date. This grey is always a clue you need to run a simulation to get new data.

Now you have told AWR that you wish to measure a time waveform of TP.Sum of diagram AM using a time base of 50 ns. This is where AWR is different than most simulators. You told it what you want – it will go and take care of all the simulation settings. You just have to start the simulator. For System Diagrams the simulation button is the yellow lightning bolt with a box below it. See the center of this image:

This will start the simulation. The system simulation runs continuously by default. It is like in the lab when you turn it on, it just keeps running. When you click the start button, you should see a sinusoidal waveform in the Graph window:

That is how you run a simulation. You can clean up your desktop by going to Window->Tile. In AWR we will be adding many graphs as windows, so using the auto-tile is very helpful.

Go ahead and add the TP upMx to the graph by adding another measurement to Graph 1. You can modify things as the simulation runs, or you can pause the simulation by clicking the pause symbol next to the start system simulation button you pushed. This will pause the simulation. To stop the simulation, just click the same button you did to start. You can tell if a simulation is running because the pause symbol will be blue and not greyed out.

Run the simulation. You will notice that the time flows continually on the bottom and it is hard to see the waveforms. You can always pause the simulation to see the waveform. You should see the screen below:

The graph is not very attractive, so we will clean it up. Right click and select Properties.

You can see that you can adjust the limits or leave them as automatic or change them to Log scale. Typically the x-axis will be auto and the Left 1, or y axis, will be auto or you can specify a range. Let’s separate the low and high frequency waveforms by clicking Left 1 and then Add axis. You should now see:

Now you have to assign each measurement to each axis. Select the Measurements tab:

You can see that I selected the TP.upMx waveform and chose axis Left 2. I also unselected Use default for the legend names and typed in my own name: upMix. Click OK and the graph now looks nicer:

I changed the title of the graph by right clicking on the name Graph 1 on the left tab and selecting Rename Graph.

Now add another graph that plots the spectrum of the Sum and upMix signals. Just create a graph and add measurements as before. To find the FFT go to: Measurement Type->Spectrum and then select Measurement->PWR_SPEC. You just need to select the TP and leave everything else alone. See below and note that I have formatted the Spectrum window using the properties (set the x axis and changed the legend names).

The final task is to see how to save or export data for your reports. Select one of the windows, then Edit-> All to Clipboard. Then open a word document and select Paste. The window that was selected is now in your document.

 

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