Digital Circuit Design

Digital Circuit Design: What is Digital Design? It is not very tough to understand if you have an idea about modern computers. There is something more to know about it and we will discuss most of the parameter of Digital Circuit. At the end of the article, you get a lot.

Digital Circuit Design
Digital Circuit Design

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Digital Circuit Design
Examples of Digital Circuit
Analog and Digital Circuit Design
Digital Integrated Circuits
Logic gates
Logic families
VLSI basics
ULSI basics
GSI basics
Difference between analog and digital computer
Analog Computer
Advantages
Disadvantages
Digital Computer

Digital Circuit Design

The term digital comes from the method the computers perform operations in digits ‘0’ and ‘1’. For several years, applications of digital electronics were confined to pc systems. In today’s world, the term digital has become part of our everyday day life because of the dramatic way that digital circuits and digital techniques have become so widely used: PLC, computer automated machine control, Robotics, Embedded, energy monitoring and control, inventory management, medical science and technology, transportation, entertainment and space exploration, Mobile System and many more.

Digital circuits are this widely used in different spheres because they direct electric current to operate multiple functions, which include signal intensification, computation, and data transference. Digital circuits have many other components, such as resistors, transistors, capacitors, inductors, and diodes. Transistors are essential for digital circuits to operate. In order to imagine the connection between the components used in digital circuits, it is essential to understand how transistors work. Transistors can work like amplifiers or switches, but transistors are used as switches in digital logic circuits. They are two common types of transistors: Bipolar Junction Transistors and Metal-Oxide Field-Effect Transistors. When they are On, they let the current flow between them, so when transistors cooperate with resistors and other devices, they become an integrated circuit with various functions.

Examples of Digital Circuit

In a fashionable home, digital circuitry controls the appliances like alarm systems for security and heating/cooling systems like AC. Under the management of digital electronic equipment and microprocessors, newer automobiles have added safety features, are more energy efficient, and are easier to diagnose and correct when any fault arise. Effective management of heating, ventilation, and air-conditioning can reduce meter bills appreciably. Additionally grocery stores are using the universal product code (UPC) or bar code to check out the total sale of the orders, moreover to control inventory and replenish stock automatically. The area of medical electronics uses digital equipment, life-support systems, and monitoring system. The digital electronics is employed extensively in a replica of music. Digital replica is a smaller amount liable to electrostatic noise and so will reproduce music with bigger fidelity.

Examples of Digital Circuit

Digital electronics evolved from the principle of the 2 voltage levels. Semiconductor device, electronic equipment may simply be designed and fabricated to output in between 2 voltage levels. The two distinct levels (usually five Volt and zero Volt) are HIGH and LOW and might be described by one and zero in Digital.

Analog and Digital Circuit Design

The numerical representation of the analog signal: a quantity is represented by a voltage, current or meters the movement which is proportional to the value of that quantity.

The numerical representation digital Signal: a quantity is represented by the symbols which consist of 1 or 0.

For example: Let’s take a system in which both digital and analog circuits are used to understand better.

Analog and Digital Circuit Design

The Gif demonstrates the basic principle of a compact disk (CD) player. The function indicates that any music is stored on the CD  in digital form optical equipment like laser diode used at the head, picks up the digital data from the rotating disk. Then, this circuitry transfers the music in form of digits to the digital-to-analog converter (DAC). The digital to analog changes the digital information into an analog signal which is an electrical signal of the original music. The signal is amplified and transferred to the speaker for the listener for entertainment.

See also: analog circuit design

In any digital circuit, mainly 2 different voltage levels are used. It is represented by 1 and 0 of 2 bits. ‘1’ is for the higher voltage like 5 volts or more than that consider as 1, also referred to as ‘HIGH’ or True. At the same time, ‘0’ is for the lower voltage, also referred to as  ‘LOW’ or False. Pont to note that this method is called positive logic.  Similarly, if we reverse every case of 1 and 0 then it will be called as Negative logic. However, we mostly use Positive logic.

Thus, HIGH or True = 1 and LOW or False = 0

Digital electronics

Digital Integrated Circuits

Digital Integrated Circuits

It will be fascinating to grasp that the majority of the digital circuits utilized in trendy digital systems are digital integrated circuits known as ICs. There is a wide variety of ICs available in the market than their discrete-component counterparts. There are many integrated-circuit fabrication technologies that are accustomed to manufacturing digital ICs. Typically, fabrication technologies are TTL, CMOS, ECL, and BiCMOS. Each differs in their style of circuitry wont to give the required logical operation. For example, TTL (transistor-transistor logic) uses the bipolar transistor as its main circuit element, while CMOS (complementary-metal-oxide-semiconductor) uses the enhancement-mode MOSFET as its principal circuit component.

 Logic gates

Logic gates

Logic gates are the basic building blocks that used to design digital electronic circuitry. A logic gate has one output pins and one or more input pins. We have already discussed the output may be HIGH (1) or Low (0) totally depends on the digital level (s) at the input terminal (s). The logic gates can be used to make any digital systems which evaluate digital input and produce a particular output response based on that logic circuit design. Logic gates are

(1) INVERTER (or NOT gate) (2) AND gate (3) OR gate (4) NAND gate (5) NOR gate (6) Exclusive-OR gate (7) Exclusive- NOR gate.

 digital electronics pdf

Something to remember that The INVERTER, AND, and OR gates are the basic logic gates in the field of digital electronics. The NAND, NOR, Exclusive-OR and Exclusive- NOR gates are designed using the basic logic gates. In which NAND, NOR are the universal gates, by using them we can design not only any gate but also any digital circuitry required. You can understand it in detail using digital electronics pdf at the bottom of the post.

Logic families

Logic families

The IC (integrated circuit) technology has advanced in the last six decades step by step, small-scale integration (SSI) to medium-scale integration (MSI) to large-scale integration (LSI) to very large- scale integration (VLSI) to Ultra large- scale integration ULSI) and moving towards the giga-scale integration (GSI). At present, it is not impossible to fabricate more than one million logic gate on a very small silicon chip.  All these logic circuits are available in IC modules and are divided into several groups of ‘families’. Each family is classified by their abbreviations that denote the types of a logic circuit used. For example, RTL is for resistors-transistor logic.

The following seven types of  transistor logic families are:

  1. Resistance-transistor logic (RTL). It was the very 1st family group of logic circuits developed and packaged in form of ICs in the early 1960s.
  2. Diode-transistor logic (DLT). After RTL, DTL came into existence in the late 1960s.
  3. Transistor-transistor logic (TTL) OR (T2L). It came into existence in the 1970s.
  4. Schottky TTL. another version of TTL for improving the speed of TTL.
  5. Emitter-coupled logic (ECL). It is the fastest logic family among all.
  6. Integrated-injection logic (I2L). IIL, I2L, or I2L is one of the latest of the bipolar junction transistors (BJT) types of logic with multiple collectors.
  7. Complementary metal-oxide-semiconductor (CMOS). CMOS has the lowest power dissipation in all the logic family

VLSI basics

VLSI Basics

Very-large-scale integration (VLSI) is a subject deal with combining thousands of transistors on a single chip. It started in the early 1970s with the manufacture of complex semiconductor and communication technologies. A VLSI device commonly is known is the microcontroller microprocessors and series of ICs. Before VLSI, most of the ICs had narrow functions. A computer circuitry usually consists of a CPU, ROM, RAM and other peripherals on the motherboard. VLSI facilitate  IC designers Engg. add all of these things on a single chip.

Read more about VLSI

ULSI basics

ULSI Basics

Ultra large scale integration (ULSI), refers placing of more than one million circuit elements into one wafer of semiconductor. The Intel 486 and Pentium microprocessors is an example of ULSI technology. ULSI is very border than VLSI. It changes the face of society. Now a day’s GSI is in used

GSI basics

GSI basics

Gigascale Integration (GSI) is mostly used in microprocessor designing where integrated circuits (IC) contain more than one billion transistor gates. GSI refers to very dense and with a rapid increase in the number or amount of transistors on IC systems. GSI is a standard measurement for microprocessors; GSI shows how afar processor design has come with modern strategies. multi-core designing is one of the techniques used in GSI.

Difference between analog and digital computer

Analog Computer

We know plenty of digital computers, however, analog computers are infrequently mentioned. It does mean that they don’t exist, however, as a result of we assume, computers are digital only. We experience numerous analog computers daily, but we hardly notice them as a computer. The basic difference between analog and digital computers is the type of information or data they work. Analog computers process analog, i.e. continuously varying data type. Digital computer process data which is binary, i.e. in the form of ‘0’ and ‘1’.

Analog computers behave towards mathematical variables within the kind of physical quantities that are continuously varied. For example temperature, pressure, voltages, Current etc. The foundation of the operating of the analog computers is modeling. Any real physical method will continuously get replaced by a mathematical model having equivalent properties. Control Engineers usually convert a mechanical system to its electrical analogy to form a mathematical model for computation. This analogy or conversion of a physical process like a suspended body in spring to its electrical model and consequently the mathematical model is the basis of analog computing. After the modeling has been done the computation becomes terribly straightforward and convenient.

analog computer

Advantages

The advantages of analog computers are that they show the result in an exceedingly easy and graphical manner in a small amount of time. In a digital computer, the real-time changes need complicated programming and graphical programs. In an analogue computer, the output may be connected to a cathode-ray oscilloscope and results may be seen.

Disadvantages

The disadvantages of analog systems are that they’re not versatile and that they don’t seem to be very accurate. The accuracy of the analog computers is very compact and keen about variety for factors like unfold in circuit parameters, inaccurate assembly, wiring issues, external influences like a magnetic field, changes in ambient temperature and pressure, etc. To obtain accuracy in analog computers before a computation all operational amplifier should be checked for DC drift.

Consider some Examples of analog computer: measuring instrument, monograph, operational amplifiers, mechanical integrators, slide rules, tide predictors, electric integrators that solve partial differential equations, electronic machines that solve ordinary differential equations, machines to solve algebraic equations, the Norden bombsight, and neural networks.

Digital Computers

Digital computers deal with mathematical variables in numbers that represent distinct values of physical quantities. The advantages of digital computers are that they’re versatile, reprogrammable, accurate, and less affected by outside disturbances and noises. In contrast to analog computers, digital machines work on digits. Each variable is reborn into varieties and every number into binary kind, i.e. 0 and 1. It is only zero and one that will be used in all the calculations. All fashionable computers, laptops, desktop, palmtops, and mobiles are all digital computers.

Digital Computers

Conclusion

Digital electronics deals with 0 and 1 whereas analog deals with any continuous quantity.

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