LAB 8 - Digital Circuit Design PDF

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Digital Circuit Design...

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EGEE 303L

DIGITAL CIRCUIT DESIGN

Experiment No8; Digital Circuit Design Department of Electrical Engineering

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EGEE 303L

DIGITAL CIRCUIT DESIGN

Table of Contents Objectives......................................................................................................................................3 Introduction...................................................................................................................................3 Lab and Calculations......................................................................................................................4 Conclusions ................................................................................................................................12

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EGEE 303L

DIGITAL CIRCUIT DESIGN OBJECTIVE

I will study three digital circuits such as BJT Inverter (NOT gate), BJT-diode AND gate, and BJT-diode NAND gate. I will design these three digital circuits with resistors, transistors, and diodes. INTRODUCTION Two controllable stable states (low and high) are required to achieve logic levels, which are referred to in the binary system as ‘one’ and ‘zero’, in practical circuitry. In this experiment, three different digital circuits will be designed. The first circuit will be the inverter circuit. When the input signal is at low voltage level, the output signal will be at high level. On the other hand, the output signal will be at low level when the input signal is at high voltage level. The second circuit will be the AND gate circuit. When any of its input signals are at low voltage level, the output signal will be at low level. Contrarily, the output signal will be at high level when both input signals are at high voltage level. The third circuit will be the NAND gate circuit. When any of its input signals are at low voltage level, the output signal will be at high level. On the other hand, the output signal will be at low level when both input signals are at high voltage level.

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DIGITAL CIRCUIT DESIGN LAB AND CALCULATIONS

Table I-a

Input

+3

-3

Theoretical Output

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Table I-b

Input

Measured Output Table II-a (Theoretical truth table) Inverter Input Voltage (V) 0 5

Output Voltage (V) 5 0

AND GATE Input A (V) 0 0 5 5

Input B (V) 0 5 0 5

Output (V) 0 0 0 5

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Table II-b (Lab Work measurements) Inverter Input Voltage (V) 0 5

Output Voltage (V) 5 0

AND GATE Input A (V) 0 0 5 5

Input B (V) 0 5 0 5

Output (V) 0 0 0 5

Table III

Input

Measured Output – (a) Input terminal A connected to ground

Measured Output – (b) Input terminal A connected to +5 volts

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Table IV

Input

Measured Output – (a) Input terminal B connected to ground

Measured Output – (b) Input terminal B connected to +5 volts

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Table V NAND Gate (Theoretical) Input A (V) Input B (V) 0 0 0 5 5 0 5 5

Output (V) 5 5 5 0

NAND Gate (Measured) Input A (V) Input B (V) 0 0 0 5 5 0 5 5

Output (V) 5 5 5 0

Digital Circuits 1) Inverter Circuit

Input

Output

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DIGITAL CIRCUIT DESIGN

2) AND gate circuit

Input

Output

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DIGITAL CIRCUIT DESIGN Output

3) NAND gate circuit

Input

Output

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Input

DIGITAL CIRCUIT DESIGN

Output

RESULTS Analysis of Truth Tables All three circuits performed the logic functions predicted by the truth tables Transistor Saturation Voltage The minimum input voltage levels for which the transistor saturated are the same as predicted O V.

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DIGITAL CIRCUIT DESIGN

CONCLUSION I learned about three digital circuits such as BJT Inverter (NOT gate), BJT-diode AND gate, and BJT-diode NAND gate. I learned how to design all three digital circuits using Multisim. Also, I learned and proved how every single circuit works.

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