Ecl or current mode logic a technology for building logic gates where the emitter of a transistor is used as the output rather than its collector. Emittercoupled logic ecl is a bjtbased logic family which is generally considered as the fastest logic available. I have this homework where i have to simulate a circuit that implements an andnand gate with emitter coupled logic. The variables are designated by the alphabets such as a, b, c, x, y, z, etc. Max3658aeta and max3658beta io model maxim integrated. Bipolar bipolar junction transistors junction transistors bjts. 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. It uses four voltagecontrolled capacitors to change the frequency. Ttltransistortransistor logic ttl is a digital logic design in which bipolar transistor s act on directcurrent pulses. Bipolar logic circuits emitter coupled logic ecl timing simulation. As the current is steered between two legs of an emitter coupled pair, ecl is sometimes called.
Consequently, dctl gates have fewer components, are more economical, and are simpler to fabricate onto integrated circuits than rtl gates. This logic family, emittercoupled spintransistor logic ecstl, is an extension of emittercoupled logic ecl that leverages the advanced features of spintronic devices. An emittercoupled logic ecl gate exhibiting an improved speed power product over the circuits presented in the past is described. Bipolar bipolar junction transistors junction transistors. The logic family refers to the general physical realization of a logical element, such as the ttl, emittercoupled logic ecl, or complementary metaloxide semiconductor cmos logic families. The pair is biased with a constantcurrent source i, and one side is connected to a reference voltage v r. Introduction to electronics ii dedication human beings are a delightful and complex amalgam of the spiritual, the emotional, the intellectual, and the physical.
This is followed by a description of binmos circuit structures which allow the construction of large fanin. In the mid1940s, the first electronic digital computer, the eniac, used logic circuits based on vacuum tubes. Circuit simulation of large emittercoupled logic circuits. Binary logic consists of binary variables and logical operations. Pdf use emitter coupled logic in your rf applications. In electronics, emittercoupled logic is a highspeed integrated circuit bipolar transistor logic family. Emitter coupled logic ecl or current mode logic cml 6. As a result, none of the transistors in the gate ever enter saturation, nor do they ever get turned completely off. Emittercoupled logic is based on the use of a multiinput differential amplifier to amplify and combine the digital signals, and emitter followers to adjust the dc voltage levels.
Emitter coupled logic ecl gates were fabricated on a nepi layer. Profiles of minoritycarrier concentrations in the base and in the emitter of an npn transistor operating in the active mode. Ecl emittercoupled logic a digital circuit composed of bipolar transistors in which the emitter ends are wired together. Circuit diagrams external to motorola products are included as a means of illustrating typical. Emitter coupled logic article about emitter coupled. The second function of the output emitter followers is. Two selectable inputs, 12 lvpecl outputs, sige clock fanout. The simplest form of the differential amplifier is shown to. The adn4661 and a companion lvds receiver offer a new solution to high speed pointtopoint data transmission, and a low power alternative to emitter coupled logic ecl or positive emitter coupled logic pecl. A v refx pin is available for biasing ac coupled inputs. Emittercoupled logic ecl objective questions digital electronics objective questions.
Emittercoupled spintransistor logic request pdf researchgate. If the impedance of the line is high, the capacitive pickup is large. Ttl ics usually have fourdigit numbers beginning with 74 or 54. Experiment 2 basic logic gates implementation using.
Unfortunately, dctl has much smaller signal levels, has more. In electronics, emittercoupled logic ecl is a highspeed integrated circuit bipolar transistor logic family. The first electrically controlled logic circuits, developed at bell laboratories in 1930s, were based on relays. In applications where small signal voltages must be amplified. Ecl gates switch faster than ttl gates, but consume more power. Click on drawing below to view pdf version of schematic. Largesignal equivalentcircuit models of the npn bjt operating in the forward active mode. Ttl transistortransistor logic ecl emittercoupled logic mos metaloxide semiconductor cmos complementary metaloxide semiconductor. In addition to providing the input stage of the operational amplifier, this configuration is the foundation for emitter coupled logic ecl, a very high speed, universally employed family of logic circuits. Emittercoupled logic components emittercoupled logic or ecl circuit technology is based on using differential amplifiers in the current steering. Alternatively, if the line impedance is low, the series impedance as seen by the induced voltage is low, allowing large currents to flow.
However, it is also possible to prevent saturation by using a radically different circuit structure. The challenge that electronic desingners face today is high speed paths be. By placing the wire from the output stage of ecl logic elements near spintransistors in other parts of a circuit, additional basis logic elements can. I searched online and found the model in the picture attached, which is supposed to implement a nandand. The purpose of biasing is to establish a qpoint about which variations in current and voltage can occur in response to an ac input signal. In the bipolar category there are three basic families called, diode transistor logic dtl, transistor transistor logic ttl and. Emitter coupled logic is very fast but uses a lot of power. For lvpecl positive ecl operation, bias v cc to the positive supply and v ee to ground. Within each family, several subfamilies of logic types are. This thesis describes the algorithms implemented in a new digital emitter coupled logic ecl simulation tool called ieclsim illinois ecl simulator. Because bjts remain in active region, power dissipation signi. Integrated receiver channel circuits and structures for a. Circuit simulation of large emitter coupled logic circuits. Technology was invented in 1940s for use in vacuum tubes the basic di erentialampli er con guration was later implemented with discrete bipolar transistors.
An ecl gate with improved speed and low power in a bicmos. Here we propose the first logic family exploiting these spintransistors, extending emittercoupled logic ecl to achieve a greater range of basis logic functions. There are additionally three capacitors but they do not play a role in the basic transistor amplifier design which mainly involves setting dc voltages. Ttl transistortransistor logic ecl emitter coupled logic mos metaloxide semiconductor cmos complementary metaloxide semiconductor.
The adclk954 features 12 fullswing emitter coupled logic ecl output drivers. Todays electronic systems continue the advance to higher clock speeds operating from a single 3. These assets, coupled with good inherent logic potential, mean that conventional valves should now be the first consideration for the logic for a pneumatic circuit. Ecl uses an overdriven bjt differential amplifier with. Directcoupled transistor logic dctl is similar to resistortransistor logic rtl but the input transistor bases are connected directly to the collector outputs without any base resistors.
However, it is also possible to prevent saturation by using a radically different circuit structure, called currentmode. The basics of emittercoupled logic technical articles. It is the fastest bipolar circuit architecture available today. Sp8655a datasheet, sp8655a pdf, sp8655a pinout, equivalent, replacement sp8655a sp8659b 200mhz divide 16 emitter coupled logic divider gec plessey semiconductors, schematic, circuit. Ecl uses an overdriven bjt differential amplifier with singleended input and limited emitter current to avoid the saturated fully on region of operation and its slow turnoff behavior. Functional verification of ecl circuits including voltage regulators. Circuit idearevealing the truth about ecl circuits. As im sure most of you know, the ornor gates are the gates that are created the most with ecl technology. However, the con guration became most useful with invention of. This compatibility of logic levels at input and output is an essential requirement in the design of gate circuits. The dc analysis of npn and pnp configurations is quite different in the sense that the currents will have opposite directions and the voltages opposite polarities. In the bipolar category there are three basic families called, diode transistor logic dtl, transistor transistor logic ttl and emitter coupled logic ecl.
Each logic family has its own basic electronic circuit upon which more complex digital circuits and functions are developed. Emittercoupled logic ecl based on bjt, but removes problems of delay time by preventing the transistors from saturating very fast operation propagation delays of 1ns or less high power consumption, perhaps 60 mwgate logic levels. Pecl positivepseudo emitter coupled logic drivers and receivers are widely employed for highspeed backplanes and pointtopoint serial connections. Here we propose the first logic family exploiting these devices, extending emittercoupled logic ecl to achieve a greater range of basis logic functions. Interface between necl and lvds by scott wu introduction because of the inherent characteristics of bipolar circuit techniques, which use differential pairs for logic state switching and an emitter follower for the output stage, the ecl emitter coupled logic family has been widely used for highspeed signal interface see figure 1. What are the advantages and disadvantages of ecl over cmos. Ecl achieves its highspeed operation by employing a relatively small voltage swing and preventing the transistors from entering the saturation region. Emittercoupled logic is based on the use of the currentsteering switch introduced in section 15. Testing was limited due to a lack of a probe card for the logic analyzer. Analog and digital circuits, coordinated science laboratory, university of. The integrated circuit editor was used to layout the design based on suprem parameters. This thesis describes the algorithms implemented in a new digital emittercoupled logic ecl simulation tool called ieclsim illinois ecl simulator. Ecl uses an overdriven bjt differential amplifier with singleended input and limited.
In electronics ecl, or emittercoupled logic, is a logic family that achieves high speed by using an overdriven bjt differential amplifier with singleended input. To begin a new logic circuit design, the first step is to create a directory to hold its files. This is a noror gate using emitter coupled logic, a highspeed type of logic using transistors. Ttl transistortransistor logic ecl emitter coupled logic. Ecl emitter coupled logic, logic circuit family euro1 standardized printed circuit board size, 100 mm x 160 mm fwhm full width at half maximum gbw gainbandwidth product ieee institute ofelectrical andelectronics engineers, inc. In the 70s ecl was the fastest logic family around, by far. The simplest form of the differential amplifier is shown to the right a modified version of figure 9. Within each logic family are one or more logic series that have distinctive characteristics, relative to other series within the same logic family.
Sp8655a datasheet, sp8655a pdf, sp8655a pinout, equivalent, replacement sp8655a sp8659b 200mhz divide 16 emitter coupled logic divider gec plessey semiconductors, schematic, circuit, manual. Direct coupled transistor logic dctl electronics tutorials. Instead the input and output circuits are pushpull connected transistors with the supply voltage negative with respect to. Direct coupled transistor logic dctl is also called as integrated injection logic i 2 c circuit. Three major steps in designing emittercoupled logic ecl circuits are generating correct functional behavior, guaranteeing design rules are obeyed, and v. Hence, their elimination results in higher density circuits operating at much reduce power. Analog and digital circuits, coordinated science laboratory, university of illinois at urbanachampaign. And8020d termination of ecl devices with ef emitter follower.
These models are based on simplified circuit expressions that may include replacement of active circuit elements with ideal controlled voltage and current sources. Adn4661 single, 3 v, cmos, lvds, high speed differential. During the transition, the emittercoupled pair t1 and t3 acts as a differential amplifier with singleended input. The following logic families are the most frequently used. For a given base emitter voltage which can be adjusted we obtain ic vce characteristics at each point by i th ll t itt lt bi llh i th v f i v th bi. If you continue browsing the site, you agree to the use of cookies on this website. A standard emitter coupled logic ecl output driver typically uses a current. The major ecl disadvantage is the very high power consumption. This circuit is formed using two matched transistors q 1 and q 2, in the ce configuration whose.
Request pdf emittercoupled spintransistor logic the recent. A v refx pin is available for biasing accoupled inputs. High speed paths are typically implemented within deep submicron cmos integrated circuits. It is called a common emitter amplifier since the emitter is common to both the input circuti and the output circuit. Rc is called the collector resistor and re the emitter resistor. By far, the most common digital integrated circuits built today use cmos logic, which is fast, offers high circuit density and lowpower per gate. The adn4661 and a companion lvds receiver offer a new solution to high speed pointtopoint data transmission, and a low power alternative to emittercoupled logic ecl or positive emittercoupled logic pecl. Media in category ecl the following 20 files are in this category, out of 20 total.
Such a switch can be most conveniently realized using the differential pair shown in fig. Determine the sources current i ee, the low voltage level v l, the reference voltage level v ref and the value of resistance r. Resistors require lot of power and space on an ic chip. Emittercoupled spintransistor logic northwestern scholars. If you need a clean emitter coupled logic ecl type signal between 200mhz and 400mhz this circuit works fine. In nonsaturating architectures, the transistors store less charge in their bases and therefore switch much faster than saturating circuit architectures such as ttl. Two selectable inputs, 12 lvpecl outputs, sige clock. Logic families there are many, many ways to design an electronic logic circuit. Io inputoutput mos metaloxidesemiconductor msm metalsemiconductormetal nmos nchannelmos. Each logic circuit, or sub circuit, being designed with quartus ii software is called a project. The bipolar families of logic circuits use the bipolar transistors fabricated on the chip. Hobby circuit 200mhz400mhz voltage controlled oscillator.
By placing the wire from the output stage of ecl logic elements near spintransistors in other logic stages throughout. Suprem was used to simulate the fabrication including junction depth and sheet resistance. Logic families and their characteristics website staff ui. If either one of them is high 700 mv, then the or output is high, and the nor output is low. Circuit architecture emitter coupled logic ecl is a nonsaturating form of digital bipolar circuit architecture. The term mecl identifies motorolas emitter coupled logic. The logic family refers to the general physical realization of a logical element, such as the ttl, emitter coupled logic ecl, or complementary metaloxide semiconductor cmos logic families.
Metal oxide semiconductor field effect transistor mosfet. Interfacing pecl to lvds analog, discrete, logic, mixedsignal. Emitter coupled logic ecl slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. For the ecl inverter shown in the following sketch, the high voltage level is v h. Spice was also used to confirm the proper operation of the devices. Emittercoupled logic ecl basic ecl inverternoninverter ecl current switch 2 basic ecl inverternoninverter vtc v oh v cc according to inverting output.
Emittercoupled logic the key to reducing propagation delay in a bipolar logic family is to prevent a gates transistors from saturating. Emitter coupled logic ecl ecl circuits are fast 1 ns delays typical because they avoid saturation can drive low impedance loads such as 50. Many ttl logic gate s are typically fabricated onto a singleintegrated circuit ic. The software works on one project at a time and keeps all information for that project in a single directory folder in the file system. Interface between necl and lvds analog, discrete, logic. It was extensively used for highperformance computers made up of many mediumscale components such as the illiac iv. Find the logical swing, noise margins and noise immunities for the mecl i circuit above.
That means all the gates belonging to the bipolar family use the transistorised circuits. The input of a ttl logic gate is characterized by a multi emitter. This is a noror gate using emittercoupled logic, a highspeed type of logic using transistors. The ecl circuit operation is considered below with assumption that the input voltage is applied to t1 base, while t2 input is unused or a logical 0 is applied.
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