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ELEC 7770 Spring 2014 Advanced VLSI Design

Introduction to CAD Tools Murali Dharan 08/01/2014. ELEC 7770 Spring 2014 Advanced VLSI Design. Course Objectives. Learn basic ideas, concepts, theory and methods. Get experience with tools and techniques. VLSI Design Methods. Algorithms and architectures

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ELEC 7770 Spring 2014 Advanced VLSI Design

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  1. Introduction to CAD Tools Murali Dharan 08/01/2014 ELEC 7770 Spring 2014Advanced VLSI Design

  2. Course Objectives • Learn basic ideas, concepts, theory and methods. • Get experience with tools and techniques.

  3. VLSI Design Methods • Algorithms and architectures • High-level and software techniques • Gate and circuit-level methods • Test Power

  4. VLSI Simulation and Synthesis Tools • QuestaSim • Designing, compiling and simulating designs • LeonardoSpectrum • ASIC and standard cell synthesis • DesignArchitect-IC • Schematic Capture • HSPICE • Circuit simulation and verification

  5. Some Power Analysis Tools and Techniques • PowerPlay • Logic simulation based power estimator • PrimeTime PX • Early stage power estimator • NanoSim • Analog Circuit Engine (ACE) simulator • HSPICE • SPICE Engine simulator (Industry standard)

  6. EDA Tools Setup • Download sample.bashrc file from Dr. Nelson's website. • Rename file to .bashrc and save it on your home directory. • http://www.eng.auburn.edu/~nelson/courses/elec5250_6250/bashrc

  7. QuestaSim • Invoked using the command “vsim” at the shell prompt • Create HDL models (behavioral/structural) • Can verify functionality using simulations • Supports VHDL, Verilog, SystemC, SystemVerilog

  8. QuestaSim

  9. QuestaSim Simulation steps • After writing your HDL code, you should compile it to check for errors and/or inconsistencies. • If no errors are there, the compiled code will be available in your “work” library. • To run the simulation, you can double click the module in the “work” library.

  10. LeonardoSpectrum Synthesis Steps • Load technology library in the database • Load the HDL file in the database • Specify design constraints (timing, area) • Compile/optimize design • Generate technology specific HDL netlists • Generate reports (area, timing)

  11. Synthesis Steps • Execute “spectrum -file filename.tcl” at the shell prompt. • Tcl file contains the list of spectrum commands which are executed sequentially.

  12. Load Library • load_library /linux_apps/ADK3.1/technology/leonardo/tsmc035_typ • Available ADK libraries: • tsmc035_typ (use this for projects) • tsmc025_typ • tsmc018_typ • ami12_typ • ami05_typ

  13. Read HDL file • read {file1.vhd folder/file2.vhd “file 3.vhd”} -format VHDL (or verilog) • Syntax check and builds database (analyze) • Synthesize generic gates and black boxes (elaborate) • Technology independent logic optimization (pre_optimize)

  14. Optimize design • optimize <design> (default is current design) • Various switches can change the functionality of the command • -effort quick (one pass) or standard (multiple passes) • -area, -delay, -auto (default) • -hierarchy preserve, flatten or auto (default)

  15. Save design to file • write <filename> • -silent (no warnings or messages) • -format <format name> • Verilog (.v) • VHDL (.vhd) • SDF (.sdf) • EDIF (.edf)

  16. Area report • report_area [<filename>] • -cell_usage • -hierarchy • -all_leafs

  17. Delay report • report_delay [<filename>] • -longest_path • -end_points • -start_points • -clock_frequency • -critical_paths • -from <start_points> • -to <end_points>

  18. Spectrum Documentation • In shell prompt, type mgcdocs $LEO_DOCS • User's Manual • Reference Manual • HDL Synthesis Manual • Synthesis and Technology Manual

  19. DesignArchitect-IC • Invoked using the command “adk_daic” at the shell prompt. • Loads the ADK libraries set up at the .bashrc file. • Import the newly synthesized verilog netlist • Go to File -> Import Verilog • Mapping file $ADK/technology/adk_map.vmp

  20. DesignArchitect-IC • Click Open Schematic, and point to the folder where the design was saved. • Click Update LVS to create a SPICE netlist which will be edited and used to run the simulations. • The netlist will be named module.src.net and will be in the design folder.

  21. SPICE Netlist modifications • The length and width parameters need to be changed while keeping the ratios constant. • Change the L value to match the technology file specifications. • Change the W values w.r.t the L values such that the previous ratios are maintained. • Include the transistor technology fileshttp://ptm.asu.edu

  22. SPICE Netlist modifications • A top level module needs to be created which instantiates the primary inputs and outputs. • X_modulename signal1 signal2... modulename • .end command is added at the end of the netlist which shows the end of SPICE netlist.

  23. Useful SPICE Commands • .inc <filename> • .option post brief probe • Post stores simulation results for analysis • Brief doesn't print data file till .end statement • Probe limits output to .probe, .print, .plot, and .graph statements • .param <parameter value>

  24. SPICE Data Statements • Independent DC Sources • Vname N1 N2 Type Value • Iname N1 N2 Type Value • N1 is the positive terminal • N2 is the negative terminal • Type can be DC, AC or TRAN • Value is the value of the source • Names should prefix with V or I

  25. SPICE Data Statements • Dependent DC Sources • Vname N1 N2 PWL (T1 V1 T2 V2 ...) • Vname N1 N2 PULSE (V1 V2 Td Tr Tf PW Period) • Td – initial delay time • Tr – rise time • Tf – fall time • PW – pulse width

  26. SPICE Data Statements • Entering a vector file • .vec 'filename' • Vector Pattern definition RADIX <1, 3 or 4> <1, 3 or 4> Vname V1[MSB:LSB] V2[MSB:LSB] IO I O B Tunit ns [Period] Time1 signal1_value1 signal2_value1

  27. SPICE Data Analysis • .tran step PERIOD • Step indicates at how many intervals in the period the signals will be sampled. • PERIOD means till what time the circuit will be analyzed. • .probe v(signal_name1) v(signal_name2)... • .measure <tran> <variable> from <> to <> • .print power

  28. SPICE Simulations and Analysis • HSPICE invoked by writing “hspice” in the shell prompt. • Opens up a xterm window, then hspice is invoked for a specific netlist. • hspice -i inputfile.sp > output.out • Waveform viewer invoked using the command “ezwave” from the shell prompt. • Used to view the waveforms of the probed signals after the SPICE simulations.

  29. NanoSim • Invoked with “nsim” command at shell prompt, then typing “nanosimgui” at the xterm window. • Uses the same SPICE netlist used in HSPICE. • HSPICE more accurate, but NanoSim faster for larger circuits.

  30. References • Dr. Nelson's CAD Tools course http://www.eng.auburn.edu/~nelson/courses/elec5250_6250/ • HSPICE Reference Manual • NanoSim Reference Manual • Predictive Technology Model website http://ptm.asu.edu

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