Evolution of TTL family. • ECL. • CMOS family and its evolution. • Overview. 2 Diode-Transistor Logic (DTL) . Scaling capabilities (large integration all MOS). Logic Families – TTL, CMOS, ECL. 10 January TTL(Transistor Transistor Logic); CMOS (Complementary MOS); ECL (Emitter Coupled Logic). DTL. (Diode Transistor Logic). – Use diodes and transistors. – Input is fed TTL. ( Transistor-Transistor Logic). – Use all transistors totem pole output. ECL. ( Emitter Coupled Logic). – Non saturated logic/Current mode logic. MOS Logic Families DTL. HTL. TTL. ECL. MOS. CMOS. Basic Gate. NOR. NOR. NAND. NAND.

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Wikipedia articles needing clarification from July The positive supply terminal of the circuit is grounded while negative supply terminal is at negative 5. Powered by Create your own unique website with customizable templates. All electrical circuits must consume some power, and any change in the voltages and currents in that circuit must take at least some time. If both transistors T1 and T2 are off i.

Thus, to interface this logic family with other, a translator circuit is needed which converts negative voltages to compatible positive voltage levels. A whole range of newer families has emerged that use CMOS technology.

Why these different families exist dates back to the s when groups of logic ICs using different technologies first became available. DTL was also made by Fairchild and Westinghouse.

The Web This site. If any of the diode is conducting i.

Logic family

Diode DB is replaced by emitter-base junction of transistor labeled T2. Texas Instruments introduced the series TTL family in These xmos usually ran off a 15 volt power supply and were found in industrial control, where the high differential was intended to minimize the effect of noise. Not shown are some early obscure logic families from the early s such as DCTL direct-coupled transistor logicwhich did not become widely available.


The ECL family is oms of all logic families. This is done to minimize the effect of noise introduced by the power supply and also to protect the gate from short-circuit that might occur accidently.

A variant of DTL fmos “high-threshold logic” incorporated Zener diodes to create a large offset between logic 1 and logic 0 voltage levels. If both the inputs are LOW, then both the transistors are in cut-off i.

For the same power dissipation, Schottky transistors have a faster switching speed than conventional transistors because the Schottky diode prevents the transistor from saturating and storing charge; see Baker clamp. A family of diode logic and diode—transistor logic integrated circuits was developed by Texas Instruments for the DC Minuteman II Guidance Computer inbut these devices were not available to the public.

Logic Families – Power, Speed and Compatibility

The use of a single family within a circuit design with direct connections between ICs enables circuit designers to produce circuits consisting mainly of ICs, with few extra coupling or biasing components. Due to number of diodes used in this circuit, the speed of the circuit is significantly low.

The diodes D1, D2 and D3 are replaced by emitter-base junctions of a multiple-emitter transistor labeled T1. The diode will conduct only when corresponding input is LOW. Ideally logic gates should be able to change state immediately and consume little or no power.

As well as the basic logic functions, compatible ICs are available, which contain particular useful combinations of gates providing a convenient way of constructing more complex circuits. Since the initial devices used oxide-isolated metal gates, they were called CMOS complementary metal—oxide—semiconductor logic. This means that the current draw of CMOS devices increases with switching rate controlled by clock speed, typically.

ytl RTL family is characterized by poor noise margin, poor fan-out capability, low speed and high power dissipation.

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The diode-transistor logic, also termed as DTL, replaced RTL family because of greater fan-out capability and more noise margin. Gates built with Schottky transistors use more power than normal TTL and switch faster. These are generally used “on-chip” and are not delivered as building-block medium-scale or small-scale integrated circuits.

This page was last edited on 18 Julyat The logic gates introduced in Module 2. Cmps typical 74 series IC is shown in Fig 3. Some military applications pre-dated civilian use. It must connected to ground or supply.

Module 3.1

Cel inputs to the gate are applied through three diodes viz. Motorola Semiconductor Products Inc. Chip designers therefore had to try and reconcile the fact that higher speeds meant more power consumption, and so some families developed, using optimum speed whilst others were developed to use the minimum of power.

Transistors T3 and T4 are emitter-followers used for DC level-shifting of output voltages.

This greatly reduces the component count of dgl circuit, which among other benefits, reduces size and increases reliability. As the overall performance of these families increased they also became more compatible.

Here, p-channel devices are in series and n-channel devices are in parallel. From Wikipedia, the free encyclopedia.

The increase in portable battery powered electronic devices along with the ability of chip manufacturers to make the component parts of ICs much smaller also meant that power could be reduced and speed increased. A short list of the most important family designators of these newer devices includes:.

Logic Families – Digital Electronics

Static Dynamic Domino logic Four-phase logic. Hence, output is connected to GND i. Thus, voltage Vcc appears at output I.