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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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Thus, none of the un-used inputs of MOS device should be left unconnected. A CMOS gate draws no current other than leakage when in a steady 1 or 0 state. Due to these undesirable characteristics, this family is now obsolete. A variant of DTL called “high-threshold logic” incorporated Zener diodes to create a large offset between logic 1 and logic 0 voltage levels.

This is done to minimize the evl of noise introduced by the power supply and also to protect the gate from short-circuit that might occur accidently. Since the transistors of a standard TTL gate are saturated switches, minority carrier storage time in each junction limits the switching speed of the device. 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.

Archived from the original on Reduced energy implies less heat dissipation. This page was last edited on 18 Julyat Before the widespread use of integrated circuits, various solid-state and vacuum-tube logic systems were used but oms were never as standardized and interoperable as the integrated-circuit devices.


Hundreds of different, but directly inter-connectable logic ICs are available. For example, early digital clocks or electronic calculators may have used one or more PMOS devices to provide most of the logic for the finished product. Making direct connections between ICs of a single family or sub family is usually very rtl. If both the inputs are LOW, then both the transistors are in cut-off i.

Hons All rights reserved. A whole range of newer families has emerged that use CMOS technology.

The diodes D1, D2 and D3 are replaced by emitter-base junctions of a multiple-emitter transistor labeled T1. Introduction year is when at least some of the devices of the family were available in volume for civilian uses. However, because the logic thresholds of CMOS were proportional to the power supply voltage, CMOS devices were well-adapted to battery-operated systems with simple power supplies.

The logic gates introduced in Module 2. Thus, voltage Vcc appears at output I. With HC and HCT logic and LS-TTL logic competing in the market it became clear that further improvements were needed eck create the ideal logic device that combined high speed, with low power dissipation and compatibility with older logic families.

Some such logic families use static techniques to minimize design complexity.

Views Read Edit View history. The codes used vary between manufacturers, but package details are usually included on the IC datasheet. Even for storage of device, all pins must cjos shorted. Other such logic families, such as domino logicuse clocked dynamic techniques to minimize size, power consumption and delay.

Interconnecting any two logic families often required special techniques such as additional pull-up resistorsmox purpose-built interface circuits, since the logic families may use different voltage levels to represent 1 and 0 states, and may have other interface requirements only met within the logic family.


Early transistorized computers were implemented using discrete transistors, resistors, diodes and capacitors.

Module 3.1

Motorola Semiconductor Products Inc. The first diode—transistor logic family of integrated circuits was introduced by Signetics in As the overall performance of these families increased they also became more compatible. A family of simple resistor—transistor logic integrated circuits was developed at Fairchild Semiconductor for the Tto Guidance Computer in Note how CMOS speed has been increased and power reduced with the introduction of the 74HC High-speed CMOS although as the laws of physics demandpower consumption still increases, as the frequency at which they operate increases.

Values are very typical and would vary slightly depending on application conditions, manufacturer, temperature, and particular type of logic circuit.

Logic Families – Power, Speed and Compatibility

Retrieved from ” https: The ECL family is fastest of all logic families. However as these ICs developed, at first as SSI small scale integrated devices, with just a few transistors per chip, and then as MSI medium scale integrated devices with or more transistors, a problem arose that as more gates and therefore more transistors were packed into a single IC, the scale of integration would be limited by the power dissipation of the device.

This causes density to be reduced and complex fabrication process. The diode will conduct only when corresponding input is LOW.

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