Nnntransistor logic gates pdf

All data manipulation is based on logic logic follows well defined rules, producing predictable digital output from certain input. Logic gates digital circuit that either allows a signal to pass through it or not. There are many characteristics used to evaluate the performance of logic. It is the logic gates that produce pulses of electrical current 1s and 0s. The circuit examples in this section are based on a representative ttl family, lowpower schottky ls or lsttl. Jan 07, 2014 this video shows a few logic gates i built with some npn bjt transistors and why they work like they do. Hi guys, in this tutorial i will show you some npn transistor based logic gates. In this tutorial, we will have a brief introduction to logic gates. Introduction to logic gates not, and, nand, or, nor. Use switch behavior of mos transistors to implement logical functions. Whats the best way to implement a given logic function. An and gate is a logic circuit that only turns on an output when all the inputs are high or a logic state of 1.

Logic design unit 7 multilevel gate circuits sauhsuan wu the maximum number of gates cascaded in series between a circuit input and the output is referred to as the number of levels of gates anror circuit a level of and gates followed by a or at the output orand circuit a level of or gates followed by a and at the output. Similarly a flipflop can be built by using a combination of logic gates and the logic gates itself can be built by using a few transistors. Hence we consider only positive logic for studying the operation of logic gates. In this configuration there are two transistors connected in series. Transistors are tiny semiconductor devices that can act as either switches or amplifiers. This is the basis for the operation for your computer and any. Equivalency says that two series transistors with wl is the same as one transistor with w2l voltage at gate of q3 is the same, it just takes longer to rise. The first take a small current at the base, and converts it to a larger current between t.

Superconducting nanotransistor based digital logic gates. The other side consists of a number of transistors two in the case shown, connected in. What is logic gate and, or, xor, not, nand, nor and xnor. To know more about boolean logic take a look boolean logic. Photonic logic gates use nonlinear optical effects. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and unlimited fanout, or it may refer to a nonideal physical device see ideal and real opamps. How to make all the logic gates from a field effect transistor, or from other logic gates.

From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20. The fanout of a logic gate is the number of inputs that the. This allows the designer to fabricate logic by connecting the opencollector outputs of several logic gates together and providing a single external pullup resistor. Ttl nor and or gates chapter 3 logic gates pdf version. What you need a breadboard a bunch of 5k and 10k resistors, and transistors a led you can use any npn type transistor for example 2n3904, bc547, bc548, bc549 etc. These have the same function as resistors of limiting the current flow when the. The use of transistors for the construction of logic gates depends upon their utility as fast switches. Rtl was made from discrete transistors and resistors and manufactured on printed circuit boards with several gates per board. Diodes and transistors pdf 28p this note covers the following topics.

Basic 1 or 2 input boolean gate 1 4 transistors pentium iii. Dynamic dvdt rating vds v 100 available repetitive avalanche rated rdson. Write a logic function that is true if and only if x contains at least two 1s. The reader will first see how logic gates can be constructed from transistors and then how digital logic functions are constructed using those gates. Transistor transistor logic gate electronics tutorials. If a string of inputs are logic 0 and the series diodes are conducting, then the output from the final stage should be recognized as a logic 0 as well. Diode logic was used extensively in the construction of early computers, where semiconductor diodes could replace bulky and costly active vacuum tube elements. In part i you probably assumed correctly that any input not connected to anything would be low. Opencollector outputs of some gates have a higher maximum voltage, such as 15v for the 7426, useful when driving other than ttl loads. Cmos technology and logic gates poly only 15,432,758 more meta pdiff ndiff mosfets to do. However, during turn off, q1 functions as a transistor thereby reducing the storage charge as will be obvious below. In this project, we will show how to build an and gate circuit with diodes. In this configuration there are two transistors connected in parallel. In logic circuits, the transistor acts as a switch with two states on and off.

Chapter 5 diode transistor logic university of babylon. Zion standard ttl logic inverter model 2 r l i l t computer engineering technology g. Lab 1 part 2 identify the 7400 series ttl gates and look up their data sheets. Logic gate from wikipedia, the free encyclopedia a logic gate is an arrangement of controlled switches used to calculate operations using boolean logic in digital circuits. The ability to perform logic operations is an essential requirement for the use of polymerbased transistors in. The digital logic gate is the basic building block from which all digital electronic circuits and microprocessor based systems are constructed from. Introduction the ta will show you the emitter, base and collector for the transistor. At any given moment, every terminal is in one of the two binary conditions false high or true low. Some circuits may have only a few logic gates, while others, such as microprocessors, may have millions of them. A logic gate is a building block of a digital circuit. In this electronics 201 lecture, we look at how to construct any logic gate imaginable from simple npn transistors using not logic. From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20 computer science cornell university. Digital electronicslogic gates basics,tutorial,circuit. On the other hand, in a negative logic system, the more negative of the two discrete levels is taken as logic 1 and the other level as logic 0.

Typically, logic diagrams are black and white, and. Describe in your lab report each of their functions. They are primarily implemented electronically but can also be constructed using electromagnetic relays. A logic gate is an idealized or physical electronic device implementing a boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. The nanotransistor is a superconducting weaklink device that has integrated hotphonon injector heaters. Transistors and logic gates uw computer sciences user pages logic gates. This is a transistor transistor logic ttl and gate circuit using bipolar junction transistors. At school level, digital logic circuits are relatively simple. We describe the fabrication and digital logic operation of superconducting nanotransistors. When the baseemitter diode is turned on enough to be driven into saturation, the collector voltage with respect to the emitter may be near zero and can be used to construct gates for the ttl logic family. The concept of memory is then introduced through the construction of an sr latch and then a d flipflop. Combinational logic circuit output depends only on the current inputs stateless sequential logic circuit output depends on the sequence of inputs past and present. A basic circuit using any generalpurpose bipolar transistor such as the bc549, bc548, or bc547, could be used to construct the gate. Ttl nor and or gates logic gates electronics textbook.

Stroud combinational logic design 106 7 functionally complete set of gates if any digital circuit can be built from a set of gates, that set is said to be functionally complete functionally complete sets of gates. Logic gates are considered to be the basics of boolean logic. Anne bracy cs 3410 computer science cornell university the slides are the product of many rounds of teaching cs 3410 by professors weatherspoon, bala, bracy, and sirer. Most logic gates take an input of two binary values, and output a single value of a 1 or 0. Logic gates logic gates perform basic logical functions and are the fundamental building blocks of digital integrated circuits. Simple basic digital logic gates simple digital logic gates can be made by combining transistors, diodes and resistors as discrete components. Let us investigate some of such circuits using dioderesistor logic drl, diode transistor logic dtl and transistor transistor logic ttl as described below. How to build more complex combinational logic using gates build adders, multiplexer, decoder, storage devices using simple gates and,not, or build a whole computer using complex logic devices assemble all the pieces together into an orchestra this is the cpu.

Logic gates have been made out of dna see dna nanotechnology and used to create a computer called maya see mayaii. A ttl device employs transistor s with multiple emitters in gates having more than one input. Introduction to digital logic with laboratory exercises. If any of the logic gates becomes logic low transistor conducting, the combined output will be low. The current drive of the transistor gate tosource voltage is reduce significantly as v.

Cmos technology and logic gates mit opencourseware. Diode logic dl, or dioderesistor logic drl, is the construction of boolean logic gates from diodes. This is a transistor transistor logic ttl or gate circuit using bipolar junction transistors. Here we report integrated chemical logic gates based on ion bipolar junction transistors. Logic gates with transistors basical logic gates mae using transistors this project is about making logic gates not, and, or using npn transistors like bc547. Digital electronics verify that the logic of the 7402 nor gate is identical to the basic unit using one of the gates in the module. Transistor q1 thus acts as a backtoback diode rather than as a transistor. Read about ttl nor and or gates logic gates in our free electronics textbook network sites. This turns them into nand and nor gates, either of which can be used to create any other kind of logic function. For the nand logic, the transistors are in series, but the output is above them. Figure 3a gives the circuit symbol and boolean expression for nor gate while figure 1b gives the twoinput truth table. Actually, there are many different ttl families, with a range of speed, power consumption, and other characteristics. Multiplexers to show a set of gates is functionally complete. Basic digital logic gates perform logical operations of and, or and not on binary numbers.

A clock is created to be used in a basic state machine. Digital logic gates the electrical circuits which perform logical operations are called gates. Also, trace the directions of all currents in this circuit. Diode transistor logic 1 chapter 5 diode transistor logic resistor transistor logic was an early form of logic used in the 1950s and early 1960s. Crude logic gates circuits may be constructed out of nothing but diodes and resistors. V s will initially charge up quickly, but the tail end of the transient is slow. Logic gates from resistors, diodes, and transistors. Realize the ex or gates using minimum number of nand gates.

A combination of gates make up a circuit and some digital circuits can be extremely complex. Transistor and logic gates laboratory instruction today you will learn how to use a transistor to amplify a small ac signal as well as using it as a switch to construct digital logic circuits. Also show their logic symbol, use the function in an equation and show the truth table for one gate in each of the integrated circuits. This is a logic family which is mainly build up of npn transistors, pn junction diodes and diffused resistors. Transistors can be used as switches and based on the connection they can be used to implement various logic gates. This article explains the basic logic gates like not gate, and gate, or gate, nand gate, nor gate, exor gate and exnor gate with their corresponding truth tables and circuit symbols. An nmos switch is on when the controlling signal is high and is off when the controlling signal is low. Its principle drawback is the fact that circuits using ttl draw more current than equivalent circuits using metal oxide semiconductor mos logic. Transmission gates, latches voltage drop of nch x gates martin, c5. There are two main types of transistors bipolar and fieldeffect. A manufacturer of integrated circuits can lay down a pattern of one type of gate, and then implement any digital logic function by modifying how the gates are connected. Jun 28, 2015 how to make all the logic gates from a field effect transistor, or from other logic gates.

Digital electronics and logic circuits role of transistors. A pmos transistor acts as an inverse switch that is on when the controlling signal is low and off when the controlling signal is high. And, or, nand, and nor and the four gates i built in this video. We will see the different logic levels in ttl circuits, cmos circuits, some simple logic gates like or, not, nand, and, etc. Ratio gate count transistor count is roughly 110 ic logic gates fall under ssi, combinational logic circuits fall under msi, and microprocessor system come under. Introduction to logic gates using transistor technology, we can create basic eve engels, 2006 slide 1 of 20 logic gates that perform boolean operations on high 5v and low 0v signals. An or gate immediately followed by a not gate constitutes the ornot or nor gate. What are the logic low and high levels of ttl ics and cmos ics. Two types of transistors commonly used in implementing logic circuits are bjts and mosfets. Ttl logic gates are rapidswitching devices the sn7400, for example, takes just 15 ns to change state. Logic gates can be made from quantum mechanical effects though quantum computing usually diverges from boolean design. Like an operational amplifier or 555 timer ic is built by combination of many transistors, flipflops, logic gates and other combinational digital circuits. Introduction to computer engineering csece 252, fall 2012. If a gate drives several similar gates in parallel problems may occur.

Building functions from logic gates weve already seen how to implement truth tables using and, or, and not an example of combinational logic. Basic semiconductor physics, diodes, the nonlinear diode model, load line analysis, large signal diode models, offset diode model, transistors, large signal bjt model, load line analysis, small signal model and transistor amplification. What is the difference between logic gates and transistors. The ttl family is based on the bipolar junction transistor, and was the first commonly available series of logic elements. Give the truth table for exnor and realize using nand gates. So enter dtl diode transistor logic, which adds an npn transistor to the output of the gates described above. The standard ttl short for transistor transistor logic logic gate was first marketed in 1963 under part numbers 74xxx. Most logic gates have two inputs and one output and are based on boolean algebra. A gate is an electronic device which is used to compute a function on a two valued signal. For example, suppose we wire up five dioderesistor and gates in series. So,in a way we can say logic gates are transistors. Quality of design quality of a hardware design primarily judged by.

The full form of ttl is transistor transistor logic. Ttl is characterized by high switching speed in some cases upwards of 125 mhz, and relative immunity to noise. From transistors to gates to logic circuits logic gates from transistors truth tables. Successful coupling of these gates into ring oscillators demonstrates that these logic gates can switch subsequent gates and perform logic operations. Digital logic or gate digital gates electrical technology. The basic building block of this logic family is nand gate and there are various subfamilies of this logic gate those are standard ttl, advanced schottky ttl, schottky ttl, low power ttl, high power ttl, fast ttl etc. With diode logic, it is also difficult to build any gates other than and and or. Transistor transistor logic topics the most commonly used bipolar logic family is transistor transistor logic. Examples of this type of gate are the 7401 and 7403 series.

From transistorsto logic gates and logic circuits prof. Both positive and negative logic are used in digital systems. Digital logic symbols we generally dont draw individual transistors in diagramming digital logic circuits. Cpl is a static gate, because outputs are connected to vdd or gnd through a lowresistance path high noise resilience.