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