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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All electrical circuits must consume some power, and any change in the voltages and currents in that circuit must take at least some time.

Logic family

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.

This page was last edited on 18 Julyat CMOS Complimentary Metal Oxide Semiconductor chips, designed for minimum power, got faster and TTL families, using bipolar transistors for optimum speed, were developed that not only increased speed but also reduced power consumption. ICs of different families can sometimes also be directly connected together, but may require some extra circuitry at the interface of the two IC ec, to maintain compatibility.

Many motherboards have a voltage regulator module to provide the even lower power supply voltages required by many CPUs.

This causes density to be reduced and complex fabrication process. A large collector current of T1 is in such direction that it helps removing base charge of T2 and T3. Hence this dgl of logic gates is modified to transistor-transistor logic i.


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

However as tyl 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.

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cmps This was made by Texas Instruments as their “51XX” series. 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. After studying this section, you should be able to: Static Dynamic Domino logic Four-phase logic.

The PMOS and I 2 L logic families were used for relatively short periods, mostly in special purpose custom large-scale integration circuits devices and are generally considered obsolete.

Texas Instruments soon introduced its own family of RTL. If any of the diode is conducting oms. It has come to existence so as to overcome the speed limitations of DTL family.

Logic Families – Digital Electronics

See static versus dynamic logic for some discussion on the advantages and disadvantages of each category. 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. Transistor—transistor logic uses bipolar transistors to form its integrated circuits. The list of packaged building-block logic families can be divided into categories, listed here in roughly chronological order of introduction, along with their usual abbreviations:.

Because CMOS and TTL families can now operate at similar speeds and similar power consumption, the 74HCT a CMOS sub-family compatible with Ttl pinouts and voltage levels now makes it possible to easily interface both families within ms a single design, so enabling the use mo the best features of each family.


RTL resistor-transistor logic and DTL diode-transistor logicsuccessfully used in early computers were superseded by TTL transistor-transistor logicwhich became the dominant technology.

Archived from the original on A short list of the most important family designators of these newer devices includes:. Thus transistor s T1 and T2 are connected in differential amplifier configuration.

CMOS gates can also tolerate much wider voltage ranges than TTL gates because the logic thresholds are approximately proportional to power supply voltage, and not the fixed levels required by bipolar circuits. 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.

In computer engineeringa logic family may refer to one of two related concepts. These two logic families were not readily compatible; apart from the differences in supply voltage and speed, they were not particularly pin compatible, as illustrated in Fig.

Caution for using MOS devices: A logic family of monolithic digital integrated circuit devices is a group of electronic logic rtl constructed using one of dgl different designs, usually with compatible logic levels and power supply characteristics within a family.

Module 3.1

The extremely small capacitance of the on-chip wiring caused an increase in performance by several orders of magnitude. By using this site, you agree to the Terms of Use and Privacy Policy. It could be used both with logic devices which used 3.