applied vlsi design

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

APPLIED VLSI DESIGN The second Design of Robert Gubitz and Bjoern Konieczek

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock Slide 2

First Approach

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

New ApproachReplace Ripple Look-Ahead Adder with Ripple-Carry Adder

a0b0a1b1a2b2

...c0c1c2

s2 s0s1

HAVAVA

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

New ApproachReplace Carry Save Array Multiplier with Wallace-Tree

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

New Approach

Rounding the Results to improve average Error

0 0 0 1 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 1 1 0 1 0 1 0 1 0 1 0 1 1 0 1 1 0 1 1 0 1 0 1 0

+ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

Resulting Design

Wallace - Tree Wallace - Tree Wallace - Tree

Ripple CarryAdder

Ripple CarryAdder

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock Slide 7

Results – Synthesis

First approach New Approach Enhancement

Frequency (in MHz)

77,714 113,013 +45,42%

Ncycles 41373 41373 ±0,00%

tOp (in μs)

5,32 *10-4 3,66091 *10-4 -31,19%

A(in No. FFs)

3299 2372 -28,1%

EAvg 0,5155633 0,2497012 -51,57%

Metric 794,014 32,069 -95,96%

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

Results – Back-annotated Design

First approach New Approach Enhancement

Frequency (in MHz)

77,714 97,381 +25,3%

Ncycles 41373 41373 ±0,00%

tOp (in μs)

5,32 *10-4 4,24859 *10-4 -20,14%

A(in No. FFs)

3299 2416 -26,77%

EAvg 0,5155633 0,2497012 -51,57%

Metric 794,014 38,61 -95,14%

Institute of Applied Microelectronics and Computer Engineering

College of Computer Science and Electrical Engineering, University of Rostock

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