Logic Gates

Analog Digital

- A system with a continuous  variable signal.

- A signal with discrete bands

of analog levels.

Waveforms

Noise vulnerable

Noise protected

Analog Digital

Logic Gates History Diode-Resistor Logic (DRL)

Transistor-Transistor Logic (TTL)&

Complementary Metal-Oxide Silicon (CMOS)

Diode-Transistor Logic (DTL)

Analog Logic Gates

DRL DTL TTL

CMOS

TTL (74 Series)CMOS (40

Series)

• +5 V • +3-15 V• high power consumption

• low power consumption

• cheap • expensive• not prone to static

electricity

• susceptible to static

electricity

Digital Logic Gates Integrated Circuit (IC) - a device made by

semiconductor companies from various electronic

components by combining it together.

Integrated Circuit Engr. Werner Jacobi

(1949) Siemens – 2 stage amplifierRobert Noyce

(1960)Texas Instruments – p-n junction (diode)Federico Faggin

(1968)Intel Corporation – Intel 4004

Digital Logic Gates Example of

IC:

Semiconductor

Digital Logic Gates

- a material that has resistivity between a

conductor and insulator. Static Electricity

- a charge generated by nature and transferred to

our body.

Digital Logic Gates Schematic

Symbol- represents a certain

electronic component. Schematic Diagram

- shows the detailed design of a circuit.

Digital Logic Gates Example of Schematic

Symbol:

Digital Logic Gates Example of Schematic

Diagram:

Digital Logic Gates

Truth Table/Function Table- a list of all possible output of a particular

expression.

Boolean Equation

- a statement that shows equality.

Digital Logic Gates Example of Boolean

Equation:

A + B = XExample of Truth Table:

A B X0 0 00 1 11 0 11 1 1

Digital Logic Gates Datashee

t - document made by semiconductor

companies which contains information

about the IC.

Digital Logic Gates Example of Datasheet:

Basic Logic GatesNOT Gate (SN7404 -

CD4009)

Truth TableA Q0 11 0

A

-simply inverts input signal.

Basic Logic GatesOR Gate (SN7432 -

CD4071)

Truth TableA B Q0 0 00 1 11 0 11 1 1

A + B = Q

-output signal is 0 if both inputs are 0.

Basic Logic GatesAND Gate (SN7408 -

CD4081)

Truth TableA B Q0 0 00 1 01 0 01 1 1A B = Q

-output signal is 1 if both inputs are 1.

Compound Logic Gates

Truth TableA B Q0 0 10 1 01 0 01 1 0

NOR Gate (SN7402 - CD4001)

A + B = Q

-output signal is 1 if both inputs are 0.

Compound Logic GatesNAND Gate (SN7400 -

CD4011)

Truth TableA B Q0 0 10 1 11 0 11 1 0A B = Q

-output signal is 0 if both inputs are 1.

Special Logic GatesXOR Gate (SN7486 -

CD4030)

Truth TableA B Q0 0 00 1 11 0 11 1 0

A + B = Q

-output signal is 0 if both inputs are the same.

Special Logic GatesXNOR Gate (SN7426 -

CD4077)

Truth TableA B Q0 0 10 1 01 0 01 1 1

A + B = Q

-output signal is 1 if both inputs are the same.

Example

(A + B) (AB) = Q

Draw the schematic diagram. Create truth

table.

Truth TableA B Not A (Y) AB (B) (Not A)+B

(R)Not AB (G) Q (W)

0 0 1 0 1 1 1

0 1 1 0 1 1 1

1 0 0 0 0 1 0

1 1 0 1 1 0 0

(A + B) (AB) = Q