Institut für Angewandte Mikroelektronik und Datentechnik Selected Topics in VLSI Design (Module...

Institut fürAngewandte

Mikroelektronikund Datentechnik

Selected Topics in VLSI Design(Module 24513)

Vincent Wiese

Adder Structures on FPGA and ASIC

26.04.23 © 2013 UNIVERSITÄT ROSTOCK | Fakultät für Informatik und Elektrotechnik 1





Content

1 Classification of Adders

2 Adder Structures and Characteristics1 Ripple-Carry Adder2 Carry-Select Adder3 Carr-Look-Ahead Adder4 Carry-Save Adder

3 On-Road Test with our FIR-Filter1 Procedural Method2 FPGA Results3 ASIC Results

26.04.23 2© 2013 UNIVERSITÄT ROSTOCK | Fakultät für Informatik und Elektrotechnik





1 Classification of Adders






2 Adder Structures






Ripple-Carry Adder


+ easy implementation+ small

- slow

Source: Timmermann (2008): Script „Algorithmen der Datentechnik“





Carry-Select Adder


+ faster than RCA+ decent size

- about twice as much FA as RCA- extra hardware for multiplexers and wires

Source: http://www.imd.uni-rostock.de/lehre/add/Addierer.pdf





Carry-Look-Ahead Adder


+ fastest CPA - very large

Source: http://www.imd.uni-rostock.de/lehre/add/Addierer.pdf





Carry-Save Adder


- results must be converted into non-redundant number system

- redundant numbers are bad for relational operations

Source: Timmermann (2008): Script „Algorithmen der Datentechnik“






On-Road Test with our FIR-Filter





Procedural Method


•used design of phase 1

•Direct Form I

•14 adders

•14 multipliers a 16 serial adders

•40 Bit numbers in each adder





FPGA Results


Adder f / MHz #R #LUT #LUT single

Ripple-Carry 53,378 762 5.321 60

Carry-Look-Ahead 52,440 769 5.145 61

Carry-Save* 63,084 825 8.385 79





ASIC Results


Adder f / MHz A / µm² P (dynamic) / mW P (leakage) / µW

Ripple-Carry 100 51.254 2,27 0,51

Carry-Look-Ahead 100 70.919 2,51 0,70

Carry-Save* 100 86.604 3,21 1,03

Adder f (max) / MHz A / µm² P (dynamic) / mW P (leakage) / µW

Ripple-Carry 153 - 4,39 1,01

Carry-Look-Ahead 130 111.351 5,37 1,45

Carry-Save* 156 124.173 6,70 1,70





Thank you!


Institut für Angewandte Mikroelektronik und Datentechnik Selected Topics in VLSI Design (Module...

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