TABLE OF CONTENTS Digital electronics has given us the power to accurately control extremely complex processes that were beyond our wildest dreams a few years ago [1]. It would take many volumes to cover the subject of digital technology, so in this text we can only scratch the surface. There is a place for both analog and digital circuits in instrumentation. Sensors and instrumentation functions are analog in nature. However, digital circuits have many advantages over analog circuits. Analog signals are easily converted to digital signals using commercially available analog to digital converters (ADC). In new designs, digital circuits will be used wherever possible.
Some of the advantages of digital circuits are:
Lower power requirements;
Increased cost effectiveness;
Ability to control multivariable systems simultaneously;
Ability to transmit signals over long distances without loss of accuracy and elimination of noise;
Higher speed signal transmission;
Memory capability for data storage;
Compatibility with controllers and alphanumeric displays.
[1]Jones, C. T., Programmable Logic Controllers, 1st ed., Patrick-Turner Publishing Co., 1996, pp. 17 22.
The basic building blocks used in digital circuits are called gates. The types of gates are Buffer, Inverter, AND, NAND, OR, NOR, XOR, and XNOR [2]. These basic blocks are interconnected to build functional blocks, such as encoders, decoders, adders, counters, registers, multiplexers, demultiplexers, memory, and so forth. The functional blocks are then interconnected to make systems, such as calculators, computers, microprocessors, clocks, function generators, transmitters, receivers, digital instruments, telephone systems, ADCs, and Digital to...
