1 / 12

Spezielle Anwendungen des VLSI – Entwurfs Applied VLSI design

Spezielle Anwendungen des VLSI – Entwurfs Applied VLSI design. Course and contest Adder structures Sebastian Kruse. Types of adders. Redundant Carry-Save (CSA) Redundant-Binary (RBA) Not redundant (CPA) Ripple-Carry (RCA), Manchester-Carry-Chain (MCC)

myrrh
Download Presentation

Spezielle Anwendungen des VLSI – Entwurfs Applied VLSI design

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spezielle Anwendungen des VLSI – Entwurfs Applied VLSI design Course and contest Adder structures Sebastian Kruse

  2. Types of adders • Redundant • Carry-Save (CSA) • Redundant-Binary (RBA) • Not redundant(CPA) • Ripple-Carry (RCA), Manchester-Carry-Chain (MCC) • Carry-Skip (CSK), Carry-Select (CSEL) • Carry-Lookahead (CLA), Conditional-Sum (CSUM) • Asynchronous adder

  3. Ripple-Carry adder • Serialization of full adders • Small area but slow speed • In general the best adder for FPGA • FPGA uses LUTs instead of AND, OR, XOR, NOT • Optimized logic which speeds up RCA

  4. Carry-Skip adder • Adder with square timing complexity and low area • Area compared to RCA: • Idea: parallel calculation CPA CPA CPA 0 1 0 1

  5. Carry-Lookahead adder • Fast adder with logarithm complexity but high area • Idea: carry is calculated in advance • Types of implementation (for carry generation) • Slansky • Kogge-Stone • Brent-Kung • Han-Carlson … CLA-Block

  6. Brent-Kung • Idea: use binary tree for carry propagation • Two tree structures • Carry collection • Carry redistribution carry tree inverse carry tree

  7. Comparison on FPGA • RCA • Area : 103 • Max. frequency : 431,779 MHz • CSK • Area : 125 • Max. frequency : 384,025 MHz • Brent Kung • Area : 109 • Max. frequency : 409,500 MHz

  8. Comparison on ASIC • RCA • Core size : 4634,45 µm² • Max. frequency : 3180 MHz • Pdyn : 22,154 mW • Pleak : 9,875 µW • CSK • Core size: 4324,63 µm² • Max. frequency : 2910MHz • Pdyn: 18,651 mW • Pleak : 8,346 µW • Brent Kung • Core size : 4392,61 µm² • Max. frequency : 2980 MHz • Pdyn : 19,406 mW • Pleak : 8,716 µW

  9. Thank you for your attention!

  10. Half / full adder • Half adder ((2,2)-counter) a b HA cout s • Full adder ((3,2)-counter) a b FA cin cout s

  11. Comparison of adders 80 Brent-Kung RCA CSK 60 0.4 RCA Area (mm2) 40 tp(nsec) CSK 0.2 Brent-Kung 20 0 0 0 0 10 20 10 20 Number of bits Number of bits Source: mountains.ece.umn.edu (2006)

  12. Kogge-Stone

More Related