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					Power Delivery Challenges for
High Performance Low Voltage
      Microprocessors
          Tanay Karnik
  Microprocessor Research Labs
        Intel Corporation

        November 9, 2001
  Extrapolating Moore’s Law
          10,000          ~2B Transistors                      1.8B
                                                                                        100                 ~40mm Die
               1,000                                                                                                                              36 41
                                                                                                                                          28 32
                                                              425M
                100      Transistors Double                                                         Die Size Grows 14% Pentium® Pro proc
                                             Pentium ®
Transi stors     10      Every Two Years Pentium® Pro III                     Die size              in Two Years 486 Pentium® proc
   (MT)                                                                        (mm) 10
                                               486 Pentium proc                                                            386
                  1                                                                                                  286
                                        386                                                         8080      8086
                 0.1                 286                                                                    8085
                                                                                                     8008
                       8085  8086                                                                   4004
                0.01       8080                                                                                            ~7% growth per year
                        8008                                                                                               ~2X growth in 10 years
               0.001 4004                                                                 1
                  ’70          ’80            ’90       ’00             ’10                   ’70             ’80            ’90         ’00              ’10




          100,000             ~30 GHz                       30GHz                                          Power Too High
           10,000                                            14GHz                       10,000
                                                          6.5GHz
               1,000
                        Frequency Doubles              3 GHz                              1,000        Power Grows
                        in Two Years                Pentium III proc
                                                                                                       Exponentially                 Pentium ®
Frequency        100                            Pentium ® Pro                  Power          100                                   processors
  (MHz)                                       Pentium ® proc                  (Watts)                          286
                                          486
                                                                                               10           8086 386486
                  10   8085           386                                                                8085
                             8086 286                                                                  8080
                           8080                                                                     8008
                                                                                                1 4004
                   1
                         8008
                         4004
                 0.1                                                                          0.1
                   ’70         ’80       ’90          ’00         ’10                                ’71    ’74      ’78    ’85    ’92   ’00     ’04   ’08
Making Moore’s Law Work
                   Leakage-
                   Leakage-Tolerant Design
50% Higher Clock    Low Voltage Enabling
                                                 5 GHz ALU




                                                   LDRAM
                                                  Body Bias
                     Leakage Reduction
50% Less Power     Aggressive Vcc Scaling
                                                    Sleep
                                                  Transistor
                                                 Stack Effect




                   Serial Differential Signals     6 Gbps
50% Faster Buses      Multi-
                      Multi-bit Signaling        Serial Signal
& power will limit performance
              Consumption
               Assuming constant die size           100                                                          Density
                     Leaking Power                                                                                 Hot Spot
                                                                                                                        Hot Spot




                                                          Power Density (W/cm2)
        200          Active Power                                                            10,000                                Sun’s Surface
                     Power Density




                                                                                  Power Density
                                                                                                  1,000                     Rocket Nozzle
Watts




                                                                                    (W/cm2)
                                                    50
                                                                                                                      Nuclear Reactor
        100                                                                                        100

                                                                                                              8086
                                                                                                    10 4004           Hot Plate        Pentium ®
                                                                                                        8008 8085     386             processors
                                                                                                                  286        486
                                                                                                         8080
         0                                          0                                                1
                 0.25µ    0.18µ      0.13µ   0.1µ                                                     ’70       ’80       ’90          ’00         ’10

              15mm Die, 1.5X Frequency
              Increase each Generation
      Energy Requirement
      2000

      1600
                    GWH
                                                  World
      1200                 Energy
       800
                                                          US
       400

         0
             1996

                    1998

                           2000

                                  2002

                                         2004

                                                2006

                                                          2008

                                                                   2010
                                                * Source: Lawrence Berkeley National Lab


More energy reduction initiatives required in future
  Parasitic Inductance
  Unknown Return Paths
                             Simple layouts form
                             loops which inadvertently
                             interact via magnetic
                             fields
Ldi/dt getting worse                   10000
                                                                      Pentium ® Pro
                                           1000
• Package L needs to reduce S -3



                                   dI/dt
                                                                 Pentium ® proc




                                   dI/
                                           100
Various Sources of Resonance                 10
                                                         386
                                                               486


• Package L – Die C                          1


• Socket L – Package C                            1.5u     .8u .35u    .18u   .1u



• Motherboard L – Socket C
          Die Power Delivery
  Supply currents reduce only linearly with voltage.
    – Power Density to increase

 • Surpassed hot-plate power density in 0.6u (P6)
    • Junction Temp <= 100 C is necessary (=> need to work with
      package research)
  Expect parasitics to increase
    – Capacitance will increase
    – R may reduce, but not much
    – L’s will not reduce
  Noise will increase
    – RI drops in power distribution
    – L(di/dt) noise will increase S/N will reduce
CHALLENGE: DELIVER 150A AT 0.9V COST EFFECTIVELY
    Cooling cost
                                               Larger temperature gradient requires smaller heat
                    Ta                         sink and air flow rate for dissipating the same
                                               power.




    Tj                                         Reduction in ja will increase cooling cost rapidly.

       Conventional Approaches                                   $
      Will Be Inadequate for Cooling
       1.5                              100
             Pentium® III
                              Projected
       1.0     Next      Dissipation Volume                               Hypothetical
Thermal      Generation                            Heat Sink
Budget
  o
 ( C/W)
                                  Projected    50 Volume (in3),
                                                  Airflow (CFM)
                                                                                       ja
        0.5                     Air Flow Rate
                                     Thermal
                                      Budget
          0                                    0        Maintaining larger die temperature reduces ja in
           0   50      100     150     200   250
                      Power (W)                         an active power dominated technology. In leakage
                                               power dominated technologies larger Tj will impact
                                               Pw and hence ja and cooling cost.
Server/Platform Level Challenges
  Present Data
   CPU consumes 55% Platform Power
  • Single 300-watt or 1+1 350-watt redundant power supply
    configuration for Intel servers
   15A/100V industrial server requirement
  Future Directions
   Paradigm Shifting: Move Bulk DC/DC Conversion
    and Redundancy into the Rack
   Increase the Density Of Power Conversion
    Everywhere
   Integrate Power, Mechanical and Thermal Functions
   Integrate the Design of Air movers and the System
Possible VRM Solutions
 Board VRM close to μP load with low
  impedance interconnect




 On-Package Switched DC/DC Convertors
 On-Die DC/DC Convertors
Power/Thermal Integration
 Heatsink


Processor Power




                                     Frame

Power Interconnect




     Integrated Power Delivery & Thermal
Summary
 The power challenges for next generation
  microprocessors require an Integrated Approach
 Optimum Power delivery requires VRM as close as
  possible to the load of the microprocessor
 Thorough analysis of entire power interconnect
  path is a must
 High density power delivery => High cost cooling

				
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