11

ECE 556 Design Automation of Digital Systems

ECE 556 Design Automation of Digital Systems

ByBy

Prof. Charlie Chung-Ping ChenProf. Charlie Chung-Ping Chen

ECE Department ECE Department

UW-MadisonUW-Madison

22

Outline

Microprocessor Technology Trends and Design Microprocessor Technology Trends and Design IssuesIssues

Interconnect delay trendsInterconnect delay trends Circuit type trendsCircuit type trends Research summaryResearch summary

33

Microprocessor Design Challenges

High performance ( > 500 Mhz)High performance ( > 500 Mhz) Low cost (< $100)Low cost (< $100) Low power consumption (< 10W mobile)Low power consumption (< 10W mobile) More functionality (KNI MMX)More functionality (KNI MMX) Shorter time to market (< 18 months)Shorter time to market (< 18 months) Satisfies different market segments (server, sub-$1000)Satisfies different market segments (server, sub-$1000) CompetitionCompetition ……..

Mission Impossible!

Mission Impossible!

44

Tentative Class Schedule

Technology Trends (1 class)Technology Trends (1 class) Interconnect Modeling and Optimization: (1 week)Interconnect Modeling and Optimization: (1 week)

basic routing: maze-routingbasic routing: maze-routing wire-sizing, buffer-sizing, buffer-insertionwire-sizing, buffer-sizing, buffer-insertion

Introduction to Verilog (1 week)Introduction to Verilog (1 week) Linear programming and Introduction to C and C++ language (1 week)Linear programming and Introduction to C and C++ language (1 week) Routing: (2 week)Routing: (2 week)

Clock routing (0.6 week)Clock routing (0.6 week) Global and channel routing, Tree routing (1.4 week)Global and channel routing, Tree routing (1.4 week)

Timing Analysis (1 week)Timing Analysis (1 week) Delay Characterization, Power CharacterizationDelay Characterization, Power Characterization PERL and Latch based timing analysis PERL and Latch based timing analysis

Partitioning and Placement (1.5 week)Partitioning and Placement (1.5 week) Floorplanning (1 week)Floorplanning (1 week)

55

Deal With It!

Higher clock frequencies Higher clock frequencies New processes: 0.18 micron, copperNew processes: 0.18 micron, copper Architecture levelArchitecture level

Superscalar, super-pipeline, out-of-order execution, speculative execution, Superscalar, super-pipeline, out-of-order execution, speculative execution, EPIC, VLIW, ILP, multi-threadEPIC, VLIW, ILP, multi-thread

Circuit levelCircuit level Aggressive dynamic circuits synthesisAggressive dynamic circuits synthesis Sizing, parallel re-powering, logic minimizationSizing, parallel re-powering, logic minimization

Physical DesignPhysical Design Performance-driven place and route, floorplaningPerformance-driven place and route, floorplaning Wire-sizing, buffer-sizing, buffer-insertionWire-sizing, buffer-sizing, buffer-insertion

66

77

88

99

1010

1111

1212

Size of Team ExplodesSize of Team Explodes

1313

1414

Process Overview

New process (0.18 um)New process (0.18 um) High aspect ratioHigh aspect ratio Low sheet rho (resistance)Low sheet rho (resistance) Low-Low- dielectric (capacitance) (3.55 vs. 4.10) dielectric (capacitance) (3.55 vs. 4.10) Good Electromigration propertyGood Electromigration property 6 metal layers 6 metal layers

M1 tight pitch for density (X-cap)M1 tight pitch for density (X-cap) M2-M3 middle pitch for density & performance (X-cap)M2-M3 middle pitch for density & performance (X-cap) M4-M6 high pitch (low resistance) for performance (Inductance)M4-M6 high pitch (low resistance) for performance (Inductance)

FutureFuture Copper - Less resistance more inductance effectCopper - Less resistance more inductance effect SOI - the M1 coupling strangeSOI - the M1 coupling strange

1515

0.25 Micron, 5 Layer Technology0.25 Micron, 5 Layer Technology

IEDM 96IEDM 96

1616

M6

M5

M4

M3

M2

M1

0.18 Micron, 6 Layer Technology0.18 Micron, 6 Layer Technology

IEDM 99IEDM 99

1717

5

10

15

20

25

120 130 140 150 160 170 180 190 200LGATE (nm)

Ga

te D

ela

y (

pse

c)

Vdd = 1.5V

Vdd = 1.3V

Gate Delay .v.s. ScalingGate Delay .v.s. Scaling

IEDM 99IEDM 99

1818

0

20

40

60

80

100

120

0.0 0.5 1.0 1.5 2.0 2.5 3.0Pitch (m)

Sheet R

ho (

mohm

/sq) Al, 0.25um, ref [6]

Al, 0.18um, this workCu, 0.22um, ref [7]

Interconnect Resistance Grows Super LinearlyInterconnect Resistance Grows Super Linearly

IEDM 99IEDM 99

1919

Interconnect Delay Trend

IEDM 99IEDM 99

2020

2121

2222

2323

Interconnect Complicated Design Flow

ArchitectureArchitecture

RTLRTL

LogicLogic

GateGate

LayoutLayout

Over tens of Over tens of iterations!iterations!

2424

Signal Integrity A new design challenge

CrossCapCrossCap

1

2

CrosstalkCrosstalk

2525

Inductance effect emerging

An old clock treeAn old clock tree Freq domain up to 1GhzFreq domain up to 1Ghz PVL and PRIMA with order PVL and PRIMA with order

16 find the exact16 find the exact

A newer ckt, a section of A newer ckt, a section of power gridpower grid Has L’sHas L’s PVL and PRIMA with 60th PVL and PRIMA with 60th

orderorder Frequencies more than 0.6 Frequencies more than 0.6

Ghz are not coveredGhz are not covered

Frequency (Ghz)

0 0.5 1 1.5 2-3

PRIMA

PVL|H(jw)|

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

|H(jw)|

PRIMA=PVL=EXACT

EXACT

2626

70 72 74 76 78 80-550

-500

-450

-400

Multi-Point PRIMA-34

PRIMA-80

TIM

PVL-80

Some MOR result

2727

2828

2929

Model order reduction

We need We need efficient toolsefficient tools to analyze the interconnect to analyze the interconnect dominant circuits (power grids, packages etc.) accurately dominant circuits (power grids, packages etc.) accurately in a reasonable amount of timein a reasonable amount of time

Promising Promising Model Order ReductionModel Order Reduction (MOR) techniques (MOR) techniques

Nonlinear Elements

Linear Elements

Nonlinear Elements

Reduced Model

3030

Power ConsumptionPower Consumption

P P C V C V22 f, where f, whereC = Capacitance ~ AreaC = Capacitance ~ AreaV = Supply VoltageV = Supply Voltagef = Operation Frequencyf = Operation Frequency

3131

Power TrendPower Trend

3232

Supply Voltage TrendsSupply Voltage Trends

3333

Deal With It!

InterconnectInterconnect Wire- and Repeater- SizingWire- and Repeater- Sizing Repeater InsertionRepeater Insertion Performance-driven noise-aware routingPerformance-driven noise-aware routing New material: Low resistance (Cooper), Low k material (SiN2) New material: Low resistance (Cooper), Low k material (SiN2)

GatesGates Gate SizingGate Sizing New Circuit Exploration - Dynamic Circuit, Dual VtNew Circuit Exploration - Dynamic Circuit, Dual Vt

……..

3434

Standby Power TrendStandby Power Trend

3535

Threshold Voltage v.s. Supply VoltageThreshold Voltage v.s. Supply Voltage

3636

Vt v.s. Delay

3737

Dual Vt circuitDual Vt circuit

High VtHigh Vt

Low VtLow Vt

3838

Aggressive circuit styles Aggressive circuit styles

3939

Clock delayed and Self-resetting dynamic circuitsClock delayed and Self-resetting dynamic circuits

4040

Process limitations