Basic Logic Circuits#

Learning Goals#

  • be comfortable in creating new projects in Vivado

  • be able to derive logic functions from truth tables

  • be able to define sum of products (SOP) and product of sums (POS) logic functions in Verilog

  • be able to translate a worded problem description into Verilog

Background#

Overview of the Design Process#

Source: Overview of the Design Process

A High Level View of the Design Process#

Exercise 36

You are asked to engineer an entertainment system for a student room that should have the following functions:

  • if the emergency button is pressed:

    • the motor should unroll the window curtain

    • the spotlight targeting the disco ball is activated

  • if humidity is too high:

    • the window opening motor is activated

  • if the back-to-normal button is pressed:

How is the compilation of the above functions called?

Exercise 37

Name methods for describing the required functions of a logic system?

Exercise 38

We can describe a digital circuit using various methods. How many of these are behavioral descriptions?

  • Block diagram

  • Schematic

  • Boolean function

  • Truth table

A) 0 B) 1 C) 2 D) 3 E) I don’t know

The Design Process#

Exercise 39

What are the typical steps of designing a digital circuit?

Representations of Logic Operations#

Source: Representations of Logic Operations

Exercise 40

Using which Boolean operator/s can we construct every logical function?

Exercise 41

Exclusive or, abbreviated as XOR is one of the Boolean operators.

  • What does it mean?

  • Describe it using: AND, OR, NOT

SOP and POS Circuits#

Exercise 42

What are sum of products and products of sums good for?

Exercise 43

What does product and sum mean in product of sums and sum of products?

Exercise 44

Imagine that you have a truth table with many inputs and a single output.

  • On which rows of the truth table would you focus if you want to derive the logical function in CDNF?

  • Why do we focus on these rows?

Logic Functions#

Exercise 45

A total of 16 logic functions are possible if we have two binary inputs a single binary output.

Why?

Exercise 46

How many logic functions are possible if we have three inputs and a single output?

Minterms and Maxterms#

Exercise 47

We already mentioned the terms

  • maxterm

  • product of sums

A sum is a logical expression of some Boolean variables chained by ORs.

What is the difference between a maxterm and a sum?

Electric and Electronic Switches for Logic Circuits#

Source: Electric and Electronic Switches for Logic Circuits

Switching Circuits#

Semiconductor-based Electronic Switches#

Exercise 48

Where does the name transistor come from?

Introduction to CMOS Technology#

Source: Introduction to CMOS Technology


1

De Morgan’s laws in engineering

2

transistor – Wiktionary