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Evaluating the Impact of Interconnections in Quantum-dot Cellular - - PowerPoint PPT Presentation

Jan 01, 2024 185 likes •379 views

Evaluating the Impact of Interconnections in Quantum-dot Cellular Automata (QCA) Frank Sill Torres 1,2 , Robert Wille 1,3 , Marcel Walter 2 , Philipp Niemann 1,2 , Daniel Groe 1,2 , Rolf Drechsler 1,2 1 DFKI GmbH (Germany), 2 University of Bremen

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SLIDE 1

Sill Torres – QCA

Evaluating the Impact of Interconnections in Quantum-dot Cellular Automata (QCA)

Frank Sill Torres1,2, Robert Wille1,3, Marcel Walter2, Philipp Niemann1,2, Daniel Große1,2, Rolf Drechsler1,2

1DFKI GmbH (Germany), 2University of Bremen (Germany) 3JKU Linz (Austria)

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SLIDE 2

2 Sill Torres – QCA

Outline

  • Motivation
  • Design Automation
  • Analysis Environment
  • Results
  • Conclusions
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SLIDE 3

3 Sill Torres – QCA

Motivation

Quantum-dot Cellular Automata (QCA)

  • Promising nanotechnology based on quantum dots
  • Remarkable low energy dissipation
  • Several (experimental) physical realizations based on different

concepts (Metal islands, nanomagnets, dangling bonds, …)

Metal islands Nanomagnets Dangling bonds

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SLIDE 4

4 Sill Torres – QCA

  • Challenging routing in QCA

– QCA is (nearly) planar technology

  • Current state: 1 layer for logic & routing, 1 layer for crossings
  • Outlook: low amount of layers

– Data flow must follow clocking constraint (clock 1 → clock 2 → clock 3 → … ) – Only orthogonal routing

  • Simple example:

Motivation

Interconnections

b a f

1 2 3 4 2 3 4 1

b a f

3

Routing overhead

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SLIDE 5

5 Sill Torres – QCA

  • More complex design
  • Interconnections with notable impact on Area, Delay, Energy

increase

  • Question: What is the actual impact?

Motivation

Interconnections cont’d

1 2 3 4 3 2 3 4 1 4 1 2 4 2 1 3 1 4 3 2 1 2 3 4 1

co

4 3 2 1 4

b a s

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SLIDE 6

6 Sill Torres – QCA

Design Automation

Comparison CMOS Process QCA Process Transistors and connections MOS layers QCA cells and its positions Layers of specific material No Differences Some Differences

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SLIDE 7

7 Sill Torres – QCA

Design Automation

Principal Flow

g2 g3

s a b f

1 2 3 2 3 4 1 4

HDL Description Netlist Tile (clock zone) grid Layout

1 2 3 2 3 4

s a f b

1 4

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SLIDE 8

8 Sill Torres – QCA

Design Automation

Gate Library

Routing Elements Simple Gates Complex Gates

Wire Bent wire Fanout Inverter Majority OR NOR XOR

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SLIDE 9

9 Sill Torres – QCA

  • Components of energy dissipation of QCA:
  • Dissipated energy: Eenv = Eclk + Ein – Eout
  • QCADesigner-E - Physics simulator including determination of energy

dissipation of QCA (https://github.com/FSillT/QCADesigner-E)

Design Automation

Energy Model

  • Eclk - Energy from clock

Eenv - Energy to environment Eout - Energy to neighboring cell(s) Ein - Energy from neighboring cell(s)

( )

tanh ' 2

env th

E dt λ η = Γ⋅ + Γ

∫

   

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SLIDE 10

10 Sill Torres – QCA

Design Automation

Characterized Gate library Area [µm²] Delay [tiles] Energy Disspation [meV]

  • Regl. Mode (25 GHz)

Fast mode (100 GHz)

000 ... 111 000 ... 111 Routing Elements Wire 0.01 1 0.09 ...

  • 0.82

...

  • Bent-wire

0.01 1 0.10 ...

  • 0.84

...

  • Fanout

0.01 1 0.12 ...

  • 1.15

...

  • Logic Gates

Inverter 0.01 1 0.13 ...

  • 1.19

...

  • Majority

0.01 1 0.15 ... 0.15 1.41 ... 1.41 OR 0.01 1 0.18 ...

  • 1.30

...

  • NOR

0.02 2 0.31 ...

  • 2.49

...

  • ...

... ... ... ... ... ... ... ...

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SLIDE 11

11 Sill Torres – QCA

Analysis Environment

1. Diagonal arrangement of clocking 2. Levelizing of netlist graph 3. Diagonal placement of each level 4. Routing

P&R Algorithm

2 3 3 4 1 4 2 3 1

  • 1
  • 2
  • 3
  • 4
  • 6

L1 L2 L3

2 3 3 4 1 4 2 3 1

  • 2
  • 1
  • 3

2 3 3 4 1 4 2 3 1

  • 2
  • 1
  • 3
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SLIDE 12

12 Sill Torres – QCA

  • Synthesis:

– Synthesis library (*.lib) for QCA gate library – Synopsys Design Compiler – ABC (AIG, BDD)

  • EFPL Benchmarks

Analysis Environment

Flow Benchmark name Inputs Outputs AND nodes Adder (adder) 256 129 1020 Barrel shifter (barrel) 135 128 3336 Max (max) 512 130 2865 Sine (sin) 24 25 5416 ... … … …

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SLIDE 13

13 Sill Torres – QCA

2000 4000 6000 8000 10000 1000 2000 3000 4000 5000 6000

Interconnection Overhead AND nodes of initial benchmarks

Area

AIG BDD Comm

Results

Area

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SLIDE 14

14 Sill Torres – QCA

10 20 30 40 50 60 1000 2000 3000 4000 5000 6000

Interconnection Overhead AND nodes of initial benchmarks

Delay

AIG BDD Comm

Results

Delay

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SLIDE 15

15 Sill Torres – QCA

Results

Energy Dissipation

100 200 300 400 500 600 700 1000 2000 3000 4000 5000 6000

Interconnection Overhead AND nodes of initial benchmarks

Energy (Regular)

AIG BDD Comm

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SLIDE 16

16 Sill Torres – QCA

  • QCA is a promising nanotechnology for low energy applications
  • Specific characteristics of QCA design require notable amount of

interconnections

  • Here: Evaluation of this impact
  • Results indicate high impact of Interconnections with consequences
  • n area, delay, energy
  • Requirements for future research:

– Comprehensive synthesis cost model for interconnections – New synthesis strategies with emphasis on reduction of interconnections – Exploration of new concepts (systolic arrays, logic duplication, …)

Conclusions

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SLIDE 17

17 Sill Torres – QCA

Thank you!

frasillt@uni-bremen.de

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SLIDE 18

Sill Torres – QCA

Evaluating the Impact of Interconnections in Quantum-dot Cellular Automata (QCA)

Frank Sill Torres1,2, Robert Wille1,3, Marcel Walter2, Philipp Niemann1,2, Daniel Große1,2, Rolf Drechsler1,2

1DFKI GmbH (Germany), 2University of Bremen (Germany) 3JKU Linz (Austria)