ads_tutorial - ECE145a/218a Exercise in Running the...

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1 ECE145a/218a: Exercise in Running the Simulation Tools and Introductory Circuits The exercises below are designed to **complement* your running the ADS tutorials (in ADS documentation), which are highly recommended. FIRST: MECHANICS OF ACCESSING THE PROGRAM.................................................................................2DOWNLOADING THEADSPROJECT DIRECTORY.....................................................................................................2EXAMPLES OF ADS SIMULATIONS:.........................................................................................................2BASICSPARAMETERSIMULATION.....................................................................................................................5MODELING BIPOLAR TRANSISTORS:....................................................................................................15SPICEMODEL.............................................................................................................................................15SUBCIRCUIT MODEL WITHSPICE MODELWITHIN..............................................................................................15SPARAMETERDATAFILE...............................................................................................................................22SMALLSIGNALMODELS................................................................................................................................22INTERCONNECTS.................................................................................................................................24UCSB HBT IC PROCESS CROSSSECTION...........................................................................................................24INTERCONNECT MODELS(ROUGHLY).................................................................................................................25COMMENT: ADS MOMENTUM...................................................................................................................27
2 First: Mechanics of Accessing the program. I have set up some example ADS directories to aid in getting the tools running quickly. Downloading the ADS project directoryOn my web page will be a compressed ADS project directory. This is in a ZAPPED format, which sounds like, but is not, a Zipped format. Download it using a web browser (save to disc) and then *unarchive project* to decompress it: Examples of ADS simulations: Download the project, Unarchive it as illustrated above, and open it. You should then see the following:
3 …you can open schematic editor window, by clicking on the button which looks like a schematic….but you may not need to: often the program opens itself in the state it was last saved. You can expand the file browser window to see available circuits (I have given you lots):
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5 Basic S-parameter Simulation with bias-dependent modelOpen up the file gain_testbench which I have created to calculate S-parameters: This will test for Sparameters of the subcircuit "biased_HBT". You can type the name of other subcircuits there to test them instead. You will see a "down arrow" button which is used to pop into the network hierarchy. Click on it, then on the subcircuit to move into the hierarchy.
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7 IMPORTANT: select the transistor, and double click on it and make sure that the following model parameters are set for *all* devices which you use in your circuit (only the emitter length should change): In this list Rex = 4Ohm-micron^2 is the parasitic emitter resistance per unit area emitter_sidewall=0.02

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