Digital logic states all digital electronic circuits and microprocessor based systems contain hardware. Transistortransistor logic 8 manufacturers data sheets the terminal specifications of several ttl families are shown in figure 9. We start with diode transistor logic which was one of the first logic families that were proposed. In transistor transistor logic or just ttl, logic gates are built only around transistors. Actually, there are many different ttl families, with a range of speed, power consumption, and other characteristics. It is extremely simple and inexpensive because it only uses passive components.
There are many logic families, but most are variations of ttl, cmos, or lvds. The full forms of the abbreviations ttl and cmos in reference to logic families are a. The full form of ttl is transistor transistor logic. It was build in 1961 by james l bui and commercially used in logic design in 1963. It is called transistortransistor logic because both the logic gating function and the amplifying function are performed by transistors. In this article, you will find the study notes on logic families which will cover the topics such as integrated circuits, characteristics of digital circuits, logical families, digital ic terminology, dl, rtl, dtl and ttl. Dec 30, 2018 the digital ics are designed using any of either bipolar devices or mos or a combination of both. Let us investigate some of such circuits using diode.
Vbe, and if a logic high is applied to the input, current flows into the base of transistor q3 via transistors q1 and q2, which switches. The first kind of logic families is bipolar families. So, as the name implies we use semiconductor diodes and. Dec 05, 2016 transistor transistor logic ttl is a class of integrated circuits which maintain logic states and achieve switching with the help of bipolar transistors.
Transistortransistor logic ttl is a logic family built from bipolar junction transistors. Since static cmos and pseudonmos were previously discussed, we focus the static logic section on various passtransistor logic families. The design of the digital ics takes place by making use of bipolar devices or mos or both. In contrast to static cmos primary inputs drive gate terminals. The families included here comprise of emitted coupled logic ecl, resistor transistor logic rtl, diode transistor logic dtl, transistor logic ttl, and diode logic dl. The rtl logic technology was one of the very first introduced. Bipolar transistortransistor logic introduced in 1964 texas instruments tremendous influence on the characteristics of all logic devices today standard ttl shaped digital technology standard ttl logic e. One of the prominent features of transistor transistor logic signals is the ability of the inputs of the gate rise to the logical 1 if left unconnected. Pdf on apr 20, 2017, shree krishna khadka and others published comparison of ic logic families find, read and cite all the research you. Transistortransistor logic ttl is a class of digital circuits built from bipolar junction transistors bjt and resistors.
Many logic families were produced as individual components, each containing. Transistor q1 thus acts as a backtoback diode rather than as a transistor. Transistor transistor logic families content writer. The output transistor q3 and q4 form a totem pole connection. Cmos logic families many families of logic exist beyond static cmos comparison of logic families for a 2input multiplexer briefly overview pseudonmos differential cvsl dynamicdomino complementary passgate. The first diodetransistor logic family of integrated circuits was introduced by. Bipolar transistor transistor logic ttl first introduced by in 1964 texas instruments ttl has shaped digital technology in many ways standard ttl family e.
Cmos complementary metal oxide semiconductor made from mosfets. In this article, you will find the study notes on logic families which will cover the topics such as ecl, mos inverter, nand and nor with nmos, cmos, nand and nor with cmos, logic families comparison. Current mode logic and non saturated fastest switching speed prop. Its name signifies that transistors perform both the logic function the first transistor and the amplifying function the second transistor. Ee141fall 2010 ratioed logic digital integrated circuits. Ttl and cmos characteristics purpose logic gates are classified not only by their logical functions, but also by their logical families. Tristate transistor logic and chip metal oxide semiconductor c. A general method in synthesis of passtransistor circuits. The types of logic devices are classified in families, of which the most important are ttl and cmos. Resistortransistor logic rtl sometimes also transistorresistor logic trl is a class of digital circuits built using resistors as the input network and bipolar junction transistors bjts as switching devices.
It is a logic family consisting completely of transistors. The first diodetransistor logic family of integrated circuits was introduced by signetics in 1962. In any implementation of a digital system, an understanding of a logic elements physical capabilities and limitations, determined by its logic family, are critical to proper operation. Logic family or series logic technology supply voltage volts basic details link. The logic families which fall under the first kind are called bipolar families, this include diode logic dl, emitted coupled logic ecl, resistor transistor logic rtl, diode transistor logic dtl, transistor transistor logic ttl. If, for instance, we wished to use a singlepole, singlethrow spst switch as the input device for a ttl logic gate, what is the best way to connect such a device to a ttl input. This extra output stage is known as totempole stage because three output components q3 and q4 and diode are stacked on one another. There have been many improvements in logical families such as ttl and cmos.
However, during turn off, q1 functions as a transistor thereby reducing the storage charge as will be obvious below. Output transist or q4 is again switched off, causing the output voltage to rise to the value of vcc. Each family has its own advantages and limitations. Transistor transistor logic gate electronics tutorials. Transistors are basically fancyspeak for electrically controlled switches. There are different families of logic gates in digital logic design.
Section 2 gives an overview of three conventional passtransistor logic families complementary passtransistor logic cpl, double passtransistor logic dpl, and dual value logic dvl. Transistortransistor logic first introduced by in 1964 texas instruments ttl has shaped digital technology in many ways one of the most widely used families for small and mediumscale devices rarely used for vlsi standard ttl family e. Ttl transistortransistor logic, made of bipolar transistors. When all inputs to a ttl nand gate are high, the top transistor of the totempole output. Pada suatu lingkungan ic ttl logika 0 direpresentasikan dengan tegangan 0 sampai 0,7 volt arus searah dc, direct current, sedangkan logika 1 diwakili oleh tegangan dc setinggi 3,5 sampai 5 volt. It relies on circuits built from bipolar transistors to achieve switching and maintain logic states. The number of inputs that the gate can handle properly with out disturbing the output level.
Rtl was made from discrete transistors and resistors and manufactured on printed circuit boards with several gates per board. Interconnecting any two logic families often required special techniques such as additional pullup resistors, or purposebuilt interface circuits, since the logic families may use different voltage levels to represent 1 and 0 states, and may have other interface requirements only met within the logic family. Commercially it starts with the 74 series like the 7404, 74s86 etc. This difference comes from the fact that manufacturing tolerances and. Logic families and their characteristics website staff ui. The circuit examples in this section are based on a representative ttl family, lowpower schottky ls or lsttl. Propagation delay is larger transistor transistor logic. V s will initially charge up quickly, but the tail end of the transient is slow. Logic gates in cmos indepth discussion of logic families in cmosstatic and dynamic, passtransistor, nonran tioed and ratioed logic n optimizing a logic gate for area, speed, energy, or robustness lowpower and highperformance circuitdesign techniques 6. Pdf on apr 20, 2017, shree krishna khadka and others published comparison of ic logic families find, read and cite all the research you need on researchgate. Logic gate circuits various logic families objective. A family of diode logic and diode transistor logic integrated circuits was developed by texas instruments for the d37c minuteman ii guidance computer in 1962, but these devices were.
Npn transistor schottky transistor r l i l t computer engineering technology g. The current drive of the transistor gatetosource voltage is reduce significantly as v. Diode transistor logic in dtl diode transistor logic, all the logic is implemented using diodes and transistors. Transistor transistor logic and complementary metal oxide semiconductor d. There are various logic families namely diode logic dl resistor transistor logic rtl diode transistor logic dtl emitter coupled logic ecl logic families can be classified broadly according to the technologies they are built with transistor transistor logic ttl cmos logic ttl and cmos logic family is most widely used ic.
Introduction to digital logic with laboratory exercises. Since dl does not use active components such as transistors, it does not provide. Chapter 5 diode transistor logic resistortransistor logic was an early form of logic used in the 1950s and early 1960s. Section 3 describes a general method to synthesize basic twoinput and threeinput logic. A bit of history the first transistors were fabricated in 1947 at bell laboratories bell labs by brattain with bardeen providing the theoretical background and shockley managed the activity. Ttl transistor transistor logic, made of bipolar transistors.
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. Diodetransistor logic dtl was used in the ibm 608 which was the first alltransistorized computer. It first was available in 1962 and as the name implies it used just resistors and transistors. Ecl emitter coupled logic for extremely high speeds. Triple transistor logic and chip metal oxide semiconductor b. This manual concentrates on the basic building blocks of digital electronics. For example, a certain amount of current is needed in order to operate correctly. To understand basic gate operation of following logic families. The first diode transistor logic family of integrated circuits was introduced by signetics in 1962. Digital logic families digital logic has evolved over the years and this process has led to the development of a variety of families of digital logic integrated circuits.
This set of notes cover in greater detail static logic families. Emittercoupled logic ecl based on bipolar transistors, but removes problems of storage time by preventing the transistors from saturating. Early transistorized computers were implemented using discrete transistors, resistors, diodes and capacitors. You will note the values given for various voltages and currents are quite different from those we calculated. Logic families1 study notes for electronics and communication. The trio received a nobel prize in physics for their work in 1956. In computer engineering, a logic family may refer to one of two related concepts. This is a logic family which is mainly build up of npn transistors, pn junction diodes and diffused resistors. The transistor was called a pointcontact transistor and was a type of bipolar junction transistor bjt. There are various logic families namely diode logic dl resistortransistor logic rtl diodetransistor logic dtl emitter coupled logic ecl logic families can be classified broadly according to the technologies they are built with transistortransistor logic ttl cmos logic ttl and cmos logic family is most widely used ic technologies. Transistortransistorlogic topics the most commonly used bipolar logic family is transistortransistor logic. The reader will first see how logic gates can be constructed from transistors and then how digital logic functions are constructed using those gates. 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.
The digital ics are designed using any of either bipolar devices or mos or a combination of both. Simple digital logic gates can be made by combining transistors, diodes and resistors as discrete components. Jan 16, 20 ttl uses a multimiter transistor at the input and is fast saturation logic circuit. Logic families are sets of chips that may implement different logical functions but use the same type of transistors and voltage levels for logical levels and for the power supplies. Logic families significance and types of logic families. Circuit complexity gives measure of number of transistors or gates. In fact, it combines diodes and resistors so sometimes it is known as dioderesistor logic drl. Each ic family has its own characteristics, limitations and advantages. Logic families logic families are sets of chips that may implement different logical functions, but use the same type of transistors and voltage levels for logical levels and for the power supplies. Characteristics of logic families in digital electronics. Ttl transistortransistor logic families history and. A family of simple resistortransistor logic integrated circuits was developed at. Different digital signalling technologies have been developed for logic chips, and parts that adhere to a particular signalling technology making them compatible are called a logic family. Rtl is the earliest class of transistorized digital logic circuit used.
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