gate-level minimization - basavaraj talawar · outline k-map method product-of-sums simplification...

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Gate-Level Minimization

Ch. 3. Mano & Ciletti

Outline● K-Map Method● Product-of-Sums Simplification● Don’t Care Conditions● NAND and NOR● Exclusive OR (XOR)● Parity Generation & Checking

Gate-Level Minimization● Boolean functions describe a Digital

Circuit.● Gate Level Minimization techniques

find an optimal circuit.● Done in logic Synthesis tools

Implement

K-Map Method● Simplify

Maurice Karnaugh (1924 – )

Map Method● Simplify

Map Method● Simplify

Map Method● Simplify

Map Method● Simplifiy

Map Method● Simplifiy

Map Method● Simplifiy

4-variable K-Map

4-variable K-Map

4-variable K-Map

Prime Implicant● A prime implicant is

a product term obtained by combining the maximum possible number of adjacent squares in the map

Sum-of-Products Simplification

Product-of-Sums Simplification

Product-of-Sums Simplification

Product-of-Sums Simplification

Product-of-Sums Simplification

F F

Don’t Care Conditions

Don’t Care Conditions

Don’t Care Conditions

NAND and NOR

NAND and NOR

NAND and NOR

NAND and NOR

Convert to NAND-NOR

Convert to NAND-NOR

F

Convert to NAND-NOR

Convert to NAND-NOR

F

Example

Example

Example● Implement

Example

Multilevel Nand Circuits

Multilevel Nand Circuits

NOR Implementation

NOR Implementation

NOR Implementation

NOR Implementation

NOR Implementation

NOR Implementation

F

Implement● AND-NOR, OR-NAND, NAND-

AND, NOR-OR

F=∑ (0,6)

Implement● AND-NOR, OR-NAND, NAND-

AND, NOR-OR

Implement

Implement

Implement

Exclusive OR (XOR)

XOR

XOR

XOR with AND–OR–NOT

XOR with AND–OR–NOT

XOR with NAND gates

XOR with NAND gates

XOR

XOR

Odd Function● Function to flag odd number of 1s

in a sequence of bits

Odd Function

Odd Function

Even Function

Even Function

Even Function

Parity Generation & Checking

● Error detection and correction codes

Parity Generation & Checking

● Error detection and correction codes

● Parity bit detects errors during the transmission of binary information

Parity Generation & Checking

● Error detection and correction codes

● Parity bit detects errors during the transmission of binary information

● Parity bit: Records if the total number of 1s are odd or even

Parity Generation & Checking● Error detection and correction codes● Parity bit detects errors during the transmission of

binary information● Parity bit: Records if the total number of 1s are odd or

even● Parity generator: Circuit that generates the parity bit

in the transmitter● Parity checker: circuit that checks the parity in the

receiver

Even-Parity-Generator

Even-Parity-Generator

3-bit Even-Parity Generator

Even-Parity-Checker

Even-Parity-Checker

4-bit even Parity Checker

Summary● K-Map Method● Product-of-Sums Simplification● Don’t Care Conditions● NAND and NOR● Exclusive OR (XOR)● Parity Generation & Checking

Extra

XOR

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