© 2013 IBM Corporation

POWER™ SynthesisThe transition from custom circuit design to large block synthesis in a high performance environment

Jeff Brownscheidle, Maureen Delaney, Eric Fluhr, Pat McIlmoyle, Tien Tran – IBM Systems & Technology Group

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Overview

VLSI Design: A Brief History of Recent Processor Design at IBM

Methodology Evolution: From Custom-driven to Synthesis-driven

A New Design Style: Large Block Synthesis (LBS)

Converting Custom Designs into LBS Designs

Advantages and Techniques of LBS

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A POWER™ Retrospective

0

500

1000

1500

2000

2500

Ch

ip T

ran

sis

tor

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t (m

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on

s)

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Mechanisms of Microprocessor Complexity

POWER4 POWER7

180nm technology; 412mm2 45nm technology; 567mm2

Dual Core 8-Core

Single Threaded 4-way Simultaneous Multi-Threading per core

8 Execution Units 12 Execution Units

2 Single-Precision Floating Point Units 4 Double-Precision Floating Point Units

Decimal Floating Point Unit

Vector Unit supporting VMX/AltiVec

Shared L2 cache; Off-Chip L3 cache Dedicated L2 cache per core; On-Chip L3 cache (eDRAM)

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The Conventional Approach: Less Synthesis, More Custom

ISU Generation 1 ISU Generation 2

Custom

Synthesized

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Trending Towards Synthesized Designs

64% 65%

37% 39%

24%19%

Gen 1 Gen 2 Gen 3

% of Designs % of Unit Area

ISU Generation 3Synthesized Logic

Percent of Unit

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Design Type Spectrum

5) Custom Design

1) VHDL structuring &parm customization

2) Latch, Local Clock Buffer Preplacement

3) Embedded, Un-RoutedCustom Components

4) Embedded, Fully Routed Custom Components

0) Random Logic Module (“Flat” Synthesis)

Design Effort

De

sig

n C

usto

miz

atio

n

New D

esig

n Te

chni

ques

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A New Design Type—Large Block Synthesis (LBS)

Sample Configurations Design Example

SynthesizedRandom

Logic

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The Power of LBS

“Structured” Flat Design

Flexibility & Incremental Customization

Scalability

Fast path to initial timing

Reduction in layout time

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Design Merging

Individual Designs Merged LBS

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Migrating a Design to LBS

Custom LBS

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VHDL Structuring

LatchesLatchesLatches Latches

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Summary

Large Block Synthesis: A modern, versatile alternative to custom high-performance design

Potential power and area savings over full custom design

Ability to iteratively increase custom designer input to converge toward a circuit solution

Long-term outlook: Can LBS radically influence future time-to-market expectations?