Many logic families were produced as individual components, each containing one or a few related basic. This application note provides detailed information on designing with positive emitter coupled logic pecl devices. Emitter coupled logic ecl ecl is the fastest known logic family ppt. In electronics, emittercoupled logic ecl is a logic family that achieves high speed by using an overdriven bjt differential amplifier with singleended input whose emitter current is limited to avoid the slow saturation region of transistor operation. The challenge that electronic desingners face today is high speed paths be. 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. Emittercoupled logic ecl, a bipolar family used in very highspeed electronics, can be modified and improved using spintransistors. Lvds is differential, using two signal lines to convey information. High speed paths are typically implemented within deep submicron cmos integrated circuits. Cml is a malignant myeloproliferative disorder of hematopoietic stem cells that affects 12 people per 100,000 annually and is reported to account for 1520% of adult leukemia cases. Sep 20, 2019 in electronics, emitter coupled logic ecl is a highspeed integrated circuit bipolar transistor logic family. Introduction to emitter coupled logic ecl family youtube. As a result, none of the transistors in the gate ever enter saturation, nor do they ever get turned completely off.
In electronics, emitter coupled logic ecl is a highspeed integrated circuit bipolar transistor logic family. The terminology of logic 0 and logic 1 states is introduced. Introduction as the world leader in logic, texas instruments ti offers a full spectrum. Emitter coupled logic ecl, sometimes referred to as current mode logic, is an extremely highspeed digital technology. Emittercoupled logic inel4207 spring 2012 monday, february 27, 12. Operated in emitter coupled geometry recall differential amplifier or emitter follower, transistors are biased and operate near their q point never near saturation.
Emitter coupled logic ecl logic gates engineering360. Emittercoupled logic almost always used as an acronym, ecl was, for several decades, the fastest logic family, reaching peak speeds of less than 1 nsec delay the basic concept in ecl is that in each gates output stage, there are two paths, to two different outputs, with a constant current always flowing through one of the two. However, it is also possible to prevent saturation by using a radically different circuit structure, called currentmode. The family is designed to operate with vcc 0 ground and vee 5. Emittercoupled logic ecl objective questions digital electronics objective questions. Emittercoupled logic last updated september 20, 2019 motorola ecl 10,000 basic gate circuit diagram. Emittercoupled spintransistor logic article in journal of parallel and distributed computing 74. Jul 12, 2018 emitter coupled logic ecl is a bjtbased logic family which is generally considered as the fastest logic available. The high voltage logic level v sh of a set input signal s to be applied, as a control input signal, to the set transistor 12 is higher than the high voltage logic level v ah of the complementary logic input signal a to be applied, as a. Many logic families were produced as individual components.
The first truly successful ic logic family, ttl transistortransistor logic was pioneered in 1962 beeson62. Digital electronics and pulse techniques course no. Other logic families were devised with higher performance in mind. Emitter coupled 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. For the ecl inverter shown in the following sketch, the high voltage level is v h. Cascaded spintronic computing beyond 10 ghz article pdf available in ieee journal on emerging and selected topics.
Ecl uses an overdriven bjt differential amplifier with singleended input and limited emitter current to avoid the saturated fully on region of operation and. Emittercoupled logic ecl is a bjtbased logic family which is generally considered as the fastest logic available. Digital integrated circuits have internal transistors operating in digital or switching mode. Pdf use emitter coupled logic in your rf applications. Three commonly used interfaces are pecl positivereferenced emitter coupled logic, lvds lowvoltage. The basics of emittercoupled logic technical articles. An emitter coupled logic flipflop usually will oscillate without an input signal. In most applications, ground signals are more noisefree than the power supply signals. Emitter coupled logic ecl ramblings a nice post over at the just another electronics blog. Emittercoupled logic wikimili, the free encyclopedia. Ecl logic, or emitter coupled logic is a family of very high speed logic.
Ecl achieves its highspeed operation by employing a relatively small voltage swing and preventing the transistors from entering the saturation region. It is also one of the oldest, dating back to motorolas mecl i circuits in 1962. Today, the 10 and 100 k ecl families remain in use where very high speed is required. The power dissipation of the emitter coupled spintransistor logic family is significantly less than ecl across all frequencies. As the current is steered between two legs of an emittercoupled pair, ecl is sometimes called currentsteering. Such a switch can be most conveniently realized using the differential pair shown in fig. R q 1 q 2 i eev ee v in v ref v c1 q 3 i e3 v o simplified ecl inverter example. Three commonly used interfaces are pecl positivereferenced emittercoupled logic, lvds lowvoltage. Emitter coupled logic circuit ecl electronics tutorials. In electronics, emittercoupled logic is a highspeed integrated circuit bipolar transistor logic family.
Determine the sources current i ee, the low voltage level v l, the reference. Examples of these are the current switching circuits that produced the first subnanosecond digital gates and culminated in the ecl emitter coupled logic. Because ecl, and therefore pecl, has long been the black magic of the logic world many. As the current is steered between two legs of an emittercoupled pair, ecl is sometimes called. Emitter coupled logic article about emitter coupled logic. Their inputs and outputs are shown in truth tables. Improved mecl iii circuits were introduced in the late 1960s.
Emitter coupled logic ecl ecl is the fastest known logic family for silicon integrated circuits. As the current is steered between two legs of an emittercoupled pair, ecl is. This resulted in a power consumption reduction relative to pecl. A type of current mode logic that is commonly used to build logic gates in which emitters of two transistors are connected to a current carrying resistor so that only one transistor will work at a time. A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply characteristics within a family. The 1050010100 series of emitter coupled logic is the fastest logic technology available for practical use. Pdf this article describes various analog applications of the nonsaturating fastest switching emitter coupled logic ecl devices. Emitter coupled logic families, originated in the late 1950s and remain the fastest chips. In ecl, the logic signals are referenced to the algebraically higher powersupply voltage rail, so the familys designers decided to make that 0 v the clean ground and use a negative voltage for vee.
It is called transistortransistor logic because both the logic gating function and the amplifying function are performed by transistors. An emitter coupled logic circuit 10 comprises a differential transistor pair 11a, 11a and a set transistor 12, which are all emitter coupled. Emittercoupled logic the key to reducing propagation delay in a bipolar logic family is to prevent a gates transistors from saturating. In computer engineering, a logic family may refer to one of two related concepts. In ecl, the logic signals are referenced to the algebraically. The list of acronyms and abbreviations related to ecl emitter coupled logic. Digital integrated circuits an overview sciencedirect topics. 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.
Finally found an answer and a citation from 1975, with the introduction of the kl10, until 1991, when nvax was released, the highest performance processors at dec were built with ecl emitter coupled logic technology. Emitter coupled logic ecl logic latches engineering360. Ecl, which stands for emittercoupled logic, is based on bipolar transistors and is currently the logic family with the highest speed and a high output power capability, although power consumption is also the highest. And8020d termination of ecl devices with ef emitter. Introduction static dc termination analysis a standard emitter coupled logic ecl output driver typically uses a current switching differential with an emitter follower for level shifting the output and the internal cml levels to familiar ecl levels. The ecl emitter coupled logic families, originated in the late 1950s and remain the fastest chips available, but consume more power, and because they use a negative power supply of 5.
Emitter coupled logic ecl is the fastest variety of discrete logic. Fast, hot, and not very dense, ecl was the technology of choice for highend systems, not just at dec, but at computer. Examples of these are the current switching circuits that produced the first subnanosecond digital gates and culminated in the ecl emittercoupled logic. 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. Introduction pecl, or positive emitter coupled logic, is nothing more than standard ecl devices run off of a positive power supply.
A microwave analog frequency divider in the past, because prescalers were manufactured using bipolar cmos bicmos technology, they used emitter coupled logic, which requires a fixed supply voltage that must be maintained at a minimum of 2. A conventional planar process is used for the 10k ecl series with a density of about ten gates per mm2 and a delay of 2 ns per gate. Lowvoltage positivepseudo emitter coupled logic lvpecl is the same concept as pecl, but uses a 3. Digital integrated circuits an overview sciencedirect. Interfacing between lvpecl, vml, cml and lvds levels. The 1050010100 series of emittercoupled logic is the fastest logic technology available for practical use. A leftward shift in the frequency at which the two design styles intersect can be noted, making this logic family an effective technology for highspeed applications. For the operation of emittercoupled logic and sedra smith book, 1 compared to cmos, why ecl is the faster logic family given that it requires so many transistors to propagate to output y t5 emitter node. Additionally, as more and more designs use cmosbased technology, new highspeed drivers. Circuits designed with ecl and our new eclbased logic family dissipate minimal dynamic power, causing the power dissipation to be nearly frequency. Ecl is more complicated to fabricate, covers a larger chip area, and is more expensive than any other logic family. In electronics, emittercoupled logic ecl is a highspeed integrated circuit bipolar transistor logic family.
Emittercoupled logic article about emittercoupled logic. Nov 25, 2015 in electronics, emitter coupled logic is a highspeed integrated circuit bipolar transistor logic family. The basic circuit shown in figure 1 is a combined ornor circuit and is operated from a v ee 5. A presentation on emitter coupled logic course title. Emittercoupled logic ecl family is a logic family that makes use of differential amplifiers operating in their active mode for the construction of logic gates. Texas instrumentslogic guide 20172 logic guide 2017texas instruments 2 introduction as the world leader in logic, texas instruments ti offers a full spectrum of logic functions and technologies that range from the mature bipolar and. As the current is steered between two legs of an emitter coupled pair, ecl is sometimes called. A function block can be formed by the interconnections of these logic gates. A builtin constantcurrent source provided current to the emitters. Emitter coupled logic ecl or pecl was available at the time, it is incompatible with standard logic levels, uses negative power rails, and leads to high chippower dissipation.
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