Overview of ECE6458:Gigascale IntegrationSpring 2007Prof. Jeff DavisTo explore the limits tocomputation!What is the goal of this class?Gigascale Integration10001001010.10.010.001197019801990200020102020MillionTransistorsEra of Billions of TransistorsPower is currently a big“limiter”10001001010.1Power(Watts)1970 1980 1990 2000 2010 2020Unsustainable trend!YearLeakage Power is GROWING!Source: K. Bowman, Impact of Variation sources on Circuit Performance and Design Techniques for Variation Tolerence,Presentation for Georgia Tech Seminar, April 18, 2006.50%40%30%20%10%0%1.50.70.350.180.090.05Technology (microns)Leakage Power (% of total)Interconnect IssuesTechnology Generation MOSFET Switching Delay RC delay of a 1 mm interconnect MOSFET switching energy Switching Energy of a 1mm interconnect 1 micron 20ps 1ps 300fJ 400fJ 100nm 5ps 30ps 2fJ 10fJ 35nm 2.5ps 250ps 0.1fJ 3fJ  Rwire=!WH!Lwire Cwire=!r!oWH!LwireWHρHε != RwireCwire="r"o#Lwire2H#H"• Speed• Energy Consumption• Power Dissipation/Heat Removal• Transistor Size• Noise• Parameter Fluctuations• Cost Per Function• Moore’s Law• Etc…So many possibilities! We must organize them!What are limits do we careabout?HIERARCHY OF LIMITS5. SYSTEM4. CIRCUIT3. DEVICE2. MATERIAL1. FUNDAMENTALFundamental Limits• Thermal Noise– Johnson Noise Power• Quantum Noise– Heisenberg Uncertainty Limit• Electromagnetic Propagation Speed– Speed of light limitMaterial Limits• Switching Energy Limits– Material dependence• Transit Time– Velocity Saturation Limits• SiO2 Scaling Limits– Quantum Mechanical Tunneling Limits• Random Dopant Placement• Time-of-flightDevice Limits• Interconnect Delay and Crosstalk• MOSFET Transit Time, Switching Energy,and Standby Power• Compare Bulk MOSFET to Double GateMOSFETCircuit Limits• CMOS Circuit Switching Energy and Propagation Delay• CMOS Minimum Supply Voltage• Global Interconnect Latency– Repeaters• Global Interconnect Crosstalk– Impact of inductanceSystem LimitsInterconnect Complexity• Architecture• Packaging• Timing• Size10-1210-910-610-310-6J10-9J10-12J10-15J10-18J100Ptd~ 1/S310010-310-610-910-1210-15Power [W], PDelay [s], td10-1810-1510-1210-910-610-3L-2 ! = 10-5 [s/cm-2](F = 0.1µ)L-2!~S2101010810610410210010-210-410-510-410-310-210-110-01010210-13(1000!) 10-11(100!)10-9(10!)10-7(1!)(Length)-2 [cm-2], L-2(Length)[cm], LDelay [s],