Emitter coupled logic Wikipedia. Motorola ECL 1. 0,0. In electronics, emitter coupled logic ECL is a high speed integrated circuit bipolar transistor logic family. ECL uses an overdriven BJT differential amplifier with single ended input and limited emitter current to avoid the saturated fully on region of operation and its slow turn off behavior. As the current is steered between two legs of an emitter coupled pair, ECL is sometimes called current steering logic CSL,3current mode logic CML4 or current switch emitter follower CSEF logic. In ECL, the transistors are never in saturation, the inputoutput voltages have a small swing 0. V, the input impedance is high and the output resistance is low as a result, the transistors change states quickly, gate delays are low, and the fanout capability is high. In addition, the essentially constant current draw of the differential amplifiers minimises delays and glitches due to supply line inductance and capacitance, and the complementary outputs decrease the propagation time of the whole circuit by reducing inverter count. ECLs major disadvantage is that each gate continuously draws current, which means it requires and dissipates significantly more power than those of other logic families, especially when quiescent. The equivalent of emitter coupled logic made out of FETs is called source coupled logic SCFL. A variation of ECL in which all signal paths and gate inputs are differential is known as differential current switch DCS logic. Historyedit. Yourkes current switch, c. ECL was invented in August 1. IBM by Hannon S. Yourke. Originally called current steering logic, it was used in the Stretch, IBM 7. IBM 7. 09. 4 computers. The logic was also called a current mode circuit. It was also used to make the ASLT circuits in the IBM 3. Yourkes current switch was a differential amplifier whose input logic levels were different from the output logic levels. ENGINEERING HANDBOOK. Introduction. This book was created based on years of research and experience of G. L. Huyett staff and is intended to be a consolidated. ASM Alloy Phase Diagram Database More than 40,300 binary and ternary phase diagrams and associated phase data. Also includes all inorganic systems. In current mode operation, however, the output signal consists of voltage levels which vary about a reference level different from the input reference level. In Yourkes design, the two logic reference levels differed by 3 volts. Asm Phase Diagram Handbook DefinitionConsequently, two complementary versions were used an NPN version and a PNP version. The NPN output could drive PNP inputs, and vice versa. In electronics, emittercoupled logic ECL is a highspeed integrated circuit bipolar transistor logic family. ECL uses an overdriven BJT differential amplifier with. THE CAR HACKERS HANDBOOK. Economic Survey Of India 2011-12 In Pdf on this page. A Guide for the Penetration Tester. Craig Smith. 7. Allotropy of Iron, IronIronCarbide equilibrium systemphases and their properties of the IronIron Carbide equilibrium diagram, different. The disadvantages are that more different power supply voltages are needed, and both pnp and npn transistors are required. Instead of alternating NPN and PNP stages, another coupling method employed zener diodes and resistors to shift the output logic levels to be the same as the input logic levels. Beginning in the early 1. ECL circuits were implemented on monolithic integrated circuits and consisted of a differential amplifier input stage to perform logic and followed by an emitter follower stage to drive outputs and shift the output voltages so they will be compatible with the inputs. The emitter follower output stages could also be used to perform wired or logic. Motorola introduced their first digital monolithic integrated circuit line, MECL I, in 1. Motorola developed several improved series, with MECL II in 1. MECL III in 1. 96. MHz flip flop toggle rates, and the 1. Asm Phase Diagram Handbook Of Nature' title='Asm Phase Diagram Handbook Of Nature' />The MECL 1. H family was introduced in 1. Fairchild introduced the F1. K family. whenThe ECLin. PS ECL in picoseconds family was introduced in 1. ECLin. PS has 5. 00 ps single gate delay and 1. GHz flip flop toggle frequency. Sql Server 2005 Developer Edition Crack Windows on this page. The ECLin. PS family parts are available from multiple sources, including Arizona Microtek, Micrel, National Semiconductor, and ON Semiconductor. The high power consumption associated with ECL has meant that it has been used mainly when high speed is a vital requirement. Older high end mainframe computers, such as the Enterprise System9. IBMs ESA3. 90 computer family, used ECL2. Cray 1 2. 5 and first generation Amdahl mainframes. Current IBM mainframes use CMOS. The DEC VAX 8. 00. ECL. Implementationedit. The picture represents a typical ECL circuit diagram based on Motorolas MECL. In this schematic, transistor T5 represents the output transistor of a previous ECL gate that provides a logic signal to input transistor T1 of an ORNOR gate whose other input is at T2 and has outputs Y and Y. Additional pictures illustrate the circuit operation by visualizing the voltage relief and current topology at low input voltage logical 0, during the transition and at high input voltage logical 1. ECL is based on an emitter coupled long tailed pair, shaded red in the figure on the right. The left half of the pair shaded yellow consists of two parallel connected input transistors T1 and T2 an exemplary two input gate is considered implementing NOR logic. The base voltage of the right transistor T3 is held fixed by a reference voltage source, shaded light green the voltage divider with a diode thermal compensation R1, R2, D1 and D2 and sometimes a buffering emitter follower not shown on the picture thus the emitter voltages are kept relatively steady. As a result, the common emitter resistor RE acts nearly as a current source. The output voltages at the collector load resistors RC1 and RC3 are shifted and buffered to the inverting and non inverting outputs by the emitter followers T4 and T5 shaded blue. The output emitter resistors RE4 and RE5 do not exist in all versions of ECL. In some cases 5. 0 line termination resistors connected between the bases of the input transistors and 2 V act as emitter resistors. OperationeditThe 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. During the transition, the core of the circuit the emitter coupled pair T1 and T3 acts as a differential amplifier with single ended input. The long tail current source RE sets the total current flowing through the two legs of the pair. The input voltage controls the current flowing through the transistors by sharing it between the two legs, steering it all to one side when not near the switching point. The gain is higher than at the end states see below and the circuit switches quickly. At low input voltage logical 0 or at high input voltage logical 1 the differential amplifier is overdriven. The transistor T1 or T3 is cutoff and the other T3 or T1 is in active linear region acting as a common emitter stage with emitter degeneration that takes all the current, starving the other cutoff transistor. The active transistor is loaded with the relatively high emitter resistance RE that introduces a significant negative feedback emitter degeneration. To prevent saturation of the active transistor so that the diffusion time that slows the recovery from saturation will not be involved in the logic delay,2 the emitter and collector resistances are chosen such that at maximum input voltage some voltage is left across the transistor. The residual gain is low K RCRE lt 1. The circuit is insensitive to the input voltage variations and the transistor stays firmly in active linear region. The input resistance is high because of the series negative feedback. The cutoff transistor breaks the connection between its input and output. As a result, its input voltage does not affect the output voltage. The input resistance is high again since the base emitter junction is cutoff.