Table of Contents
Programmable Logic Devices (PLDs) are essential components in digital systems, allowing customization of logic functions. Using logic gates to build these devices involves specific techniques and calculations to ensure correct operation and efficiency. This article explores the fundamental methods used in designing PLDs with logic gates.
Basic Techniques for Building PLDs
The construction of PLDs begins with the selection of appropriate logic gates such as AND, OR, and NOT gates. These gates are combined to implement desired logic functions. The primary technique involves creating a programmable array of logic gates that can be configured to perform various operations.
Interconnections between gates are established through programmable switches or multiplexers, enabling flexibility. The design process includes defining the logic functions and mapping them onto the gate array efficiently.
Techniques for Logic Function Implementation
Implementing logic functions in PLDs requires systematic methods such as sum-of-products (SOP) and product-of-sums (POS). These methods simplify the process of designing logic circuits by expressing functions in standardized forms.
For example, a function F can be represented as a sum of minterms in SOP form, which directly maps to AND-OR gate configurations. Calculations involve identifying the minterms or maxterms that satisfy the function.
Calculations for Logic Gate Design
Calculations in designing PLDs focus on minimizing the number of gates and interconnections. Boolean algebra simplifies logic expressions, reducing hardware complexity. Karnaugh maps are also used to visualize and minimize functions.
For instance, simplifying a Boolean expression like (A AND B) OR (A AND C) results in A AND (B OR C), reducing the number of gates needed. These calculations improve the efficiency and speed of the final device.