1. ELEC 5270/6270 Spring 2013 Low-Power Design of Electronic Circuits Tools for Power Analysis http://www.eng.auburn.edu/~vagrawal/COURSE/E6270_Spr13/course.html Murali Dharan January 9, 2013 1

2. Course Objectives Understand the need for low power in VLSI design. Learn basic ideas, concepts, theory and methods. Get experience with tools and techniques. 2

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

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 4

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) 5

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 6

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 7

8. QuestaSim 8

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. 9

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11. 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

12. Synthesis Steps Execute “spectrum -file filename.tcl” at the shell prompt. Tcl file contains the list of spectrum commands which are executed sequentially. 12

13. Load Library load_library /linux_apps/ADK3.1/technology/leonardo/tsmc0 35_typ Available ADK libraries:  tsmc035_typ (use this for projects)  tsmc025_typ  tsmc018_typ  ami12_typ  ami05_typ 13

14. 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

15. Optimize Design optimize (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

16. Save Design to File write -silent (no warnings or messages) -format  Verilog (.v)  VHDL (.vhd)  SDF (.sdf)  EDIF (.edf) 16

17. Area Report report_area [ ] -cell_usage -hierarchy -all_leafs 17

18. Delay Report report_delay [ ] -longest_path -end_points -start_points -clock_frequency -critical_paths -from -to 18

19. Spectrum Documentation In shell prompt, type mgcdocs $LEO_DOCS User's Manual Reference Manual HDL Synthesis Manual Synthesis and Technology Manual 19

20. 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

21. 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

22. 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.eduhttp://ptm.asu.edu 22

23. 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

24. Useful SPICE Commands.inc.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 24

25. 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

26. 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

27. SPICE Data Statements Entering a vector file .vec 'filename' Vector Pattern definition RADIX Vname V1[MSB:LSB] V2[MSB:LSB] IO I O B Tunit ns [Period] Time1 signal1_value1 signal2_value1 27

28. 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 from <> to <>.print power 28

29. 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

30. 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

31. 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 31