# 09 Adders (Part I) - EE115C Digital Electronic Circuits...

This preview shows pages 1–10. Sign up to view the full content.

EE115C igital Electronic Circuits Digital Electronic Circuits Lecture 9: Adders – Part I

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
One-Bit Full Adder The Binary Adder Full dd ut A B adder Sum C out C in SA B C i ⊕⊕ = A = BC i ABC i i i +++ C o AB BC i AC i ++ = EE115C 2
Multi-Bit Adders : Example A 0 B 0 A 1 B 1 A 2 B 2 A 3 B 3 FA FA FA FA C i ,0 C o ,0 ( = C i ,1 ) C o ,1 C o ,2 C o ,3 S 0 S 1 S 2 S 3 , t adder = ( N 1) t carry + t sum Goals very low t adder small adder (layout) area 3 adder cells should be identical, preferably EE115C

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Inversion Property A B AB C C i FA C C FA S o o i S 6 EE115C
Minimize Critical Path by Reducing Inverting Stages A 3 Even cell Odd cell A 0 B 0 A 1 B 1 A 2 B 2 B 3 FA FA FA FA C i ,0 C o ,0 C o ,1 C o ,3 C o ,2 S 0 S 1 S 2 S 3 xploit Inversion Property 7 Exploit Inversion Property EE115C

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Full Adder – Another Look… AB Full adder C out C in Sum Define 3 new variables which ONLY depend on A and B Delete = A B Generate (G) = AB Propagate (P) = A B ote: ternate definition for 8 Propagate (P) = A + B Note: alternate definition for P EE115C
S and C out as a Function of P, G, D, C in ropagate (P) = A Delete = A B Generate (G) = AB Propagate (P) A B Can also derive expressions for S and C ut based on D and P out 9 EE115C

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 04/18/2010 for the course EE 115C taught by Professor N/a during the Spring '10 term at UCLA.

### Page1 / 27

09 Adders (Part I) - EE115C Digital Electronic Circuits...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online