A TUTORIAL - Using CMU Mems Utility

Jan 28, 2000
Copyright (c) 1998, Carnegie Mellon University
All Rights Reserved.
INTRODUCTION
This tutorial details the basic steps on how to build a schematic with CMU Mems Utility instances and automatically generated layout. The schematic is shown in the graph to the left. It consists of one beam, one anchor, and one layout_origin. The layout generated from this schematic is shown at right.


Schematic


Layout 

Part I. Presteps
   If you have already done following practices, please jump to Part II.
   1. If you don't know how to start cadence, see Start Cadence
   2. If you don't know how to edit schematic, Read schematic edit help 
   to learn how to:
        A. Create a new library
        B. Create a new schematic cell view
        C. Placing an instance in a schematic editing window
        D. Some basic skills in manipulating the symbols
        E. List of required parameters for CMU Mems Utility components.
   3. Create a new library "test". Create a new schematic "tutorial" in 
      "test" library.
Part II. Steps to build schematic 1. Lets start with the beam_0010. Click on the instance icon to add a new instance. Specify Library, Cell, View, and properties as show below. Remember in order to put a vertical beam, you have to click Rotate once. Don't forget to enter in all the properties.

2. Now that we have a beam in the schematic window, let's put an anchor. Click on the instance icon to add a new instance. Specify Library, Cell, View, and properties as show below.

Place the anchor properly, your schematic window should now look like this.

3. Next click on the Wire icon. Click once on the "dx" pin of the anchor, then click once on the "xm" pin of the beam. You should see a wire is connecting to two pins. Do the same with "dy"-"ym" and "dphi"-"phim". Your schematic should now look like this.

4. Press the "Esc" key to escape wire mode. Now you should be able to figure out by yourself how to put in the layout_origin, and how to connect it. Once you finish this your schematic should look like this.

tutorial_new_sch4.gif (3602 bytes)

5. In order to simulate resonating frequency, we need to add an ac force source and a gnd. Note force_ac is from the NODAS_basic library, and gnd is from the analogLib library.

tutorial_new_force.gif (4676 bytes)

tutorial_new_gnd.gif (3726 bytes)

6. Place these instances in your schematic like the picture below.

tutorial_new_sch5.gif (4558 bytes)

7. Wire the instances properly wire and your schematic is finished. The final should schematic look like this:

Part III. Simulation

  1. After you have saved your file, in the Schematic window click on "Tools" => "Artist". An Analog Artist Simulation window will appear.

  2. Now we have to select the node we want to plot. In the Analog Artist Simulation Window, click on "Outputs" => "To Be Plotted" => "Select On Schematic". Then in the Schematic Window click on the electronic output wire of the resonator.

    3. The net becomes high-lighted in a color (in the case yellow).

  3. Now we are going to do AC analysis to find out the resonate frequency. In the Analog Artist Simulation window click "Analysis" => "Choose". A Choose Analysis window will appear.

    4. Select "ac", and set frequency range as above. Then click "Ok".

  4. Next, In the Analog Artist Simulation window click "Simulation" => "Run". After Cadence finishes calculating, a waveform window will appear.

You can see the resonating frequency is around 300k.

Part III. Layout Generation Now That we've done all the hard work, layout generation is just a few click away. First, in the schematic window, press F6. Notice there is a new menu item "Mems Utility" that appears on the top menu bar. Next. Click "Mems Utility". You will see two sub menu-items.

3. Click on "Check & Save for MEMS Schematics". In the CIW window you should see that there were no errors and that new values have been set for Xc and Yc.

 

5. Click on "Schematics => Layout" in the MEMS menu. You will see the layout pop up in a seperate window!

Note: What you see in layout is the top-level cells. If you want to see the detailed layers press Shift-F. To switch back from the layer view to top-level cell view press Ctrl-F.

Part IV. Play more with the schematic. Now go back to the schematic and try to change the properties of the beam or anchor. See how the layout will generate according to your specification. Then try to play with more complex instances like putting a plate in your schematic. Then try to put in a comb_1 and comb_2. Enjoy! If you are ready to try building some real useful application and learn how to simulate, go to How to build a folded flexure resonator .

Created 03/09/00 by Kai He at khe@ece.cmu.edu