Each IC family has its own characteristics, limitations and advantages. There have been many improvements in logical families such as TTL and CMOS. Logic (DTL); Transistor-Transistor Logic (TTL); Emitter Coupled Logic (ECL). 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 Basic Logic Families indicate the type of logic circuit used in the IC. The main types of logic families are.

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This page was last edited on 18 Julyat Fan-in input load factor is the number of input signals that can be connected to a gate without causing it to operate outside its intended operating range.

Digital Logic Families

Bipolar ICs are devices whose active components are current controlled while unipolar ICs are devices whose active components are voltage controlled. A Circuit configuration diyital arrangement of the circuit elements in a special manner will result in a particular Logic Family. All electrical circuits must consume some power, and any change in the voltages and currents in that circuit must take at least some time.

All the TTL families above have three configurations namely: In computer engineeringa logic family may refer to one of two related concepts. Sequential Logic Circuits Each family has its own characteristics, advantages and disadvantages. This is the maximum current which the gate can sink in 1 level. Hundreds of different, but directly inter-connectable logic ICs are available.

As the overall performance of these families increased they also became more compatible. The extremely small capacitance of the on-chip wiring caused an increase in performance by several orders of magnitude.


ECL was first introduced in Several techniques and design styles are primarily used in designing large single-chip application-specific integrated circuits ASIC and CPUs, rather than generic logic families intended for use in multi-chip applications.

The diodes also cannot perform the NOT operation which limits their functionality. Schottky formulated a theory predicting the Schottky effectwhich led to the Schottky diode and later Schottky transistors.

Other such logic families, such as domino logicuse clocked dynamic techniques to minimize size, power consumption and delay. Sometimes an extra transistor is needed to re-amplify the signal.

These families are listed below: Saturating type Precision HWR. Many motherboards have a voltage regulator module to provide the even lower power supply voltages required by many CPUs. Series regulator using op-amp.

Field Programmable Gate Array. A short list of the most important family designators of these newer devices includes:. There is no power dissipation in CMOS.

Transistor Transistor logic gate family IIL: Digital IC can be further categorized into elc or unipolar IC. A variant of DTL called “high-threshold logic” incorporated Zener diodes to create a large offset between logic 1 and logic 0 voltage levels. Comparator IC LM Comparator as a Duty Cycle Controller.

Logic Families – Power, Speed and Compatibility

Asymmetrical Inverting Schmitt Trigger. High-level input current, IIH: Since the initial faamilies used oxide-isolated metal gates, they were called CMOS complementary metal—oxide—semiconductor logic. Texas Instruments soon introduced its own family jos RTL. CMOS chips often work with a broader range of power supply voltages than other logic families. This greatly reduces the component count of a circuit, which among other benefits, reduces size and increases reliability.

So that it is large enough for electrical connections to be made. This is the minimum current which must be supplied by a driving source corresponding to 0 level voltage. By using this site, you agree to the Terms of Use and Privacy Policy. Many logic families were produced as individual components, each containing one or a few related basic logical functions, which could be used as “building-blocks” to create systems or as so-called “glue” to interconnect more complex integrated circuits.

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Large scale integration LSI to no of gates 4. 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.

The required silicon area for implementing such digital CMOS functions has rapidly shrunk. This is the maximum input voltage which is recognized by the gate as logic 0.

Resistor-Transistor gates are not very expensive and are very simple to construct.

Module 3.1

Although each gate only dissipates a few milliWatts, the heat generated within a single large-scale integrated LSI circuit containing tens of thousands of transistors could potentially quickly destroy the IC.

IC packaging Protect the chip from mechanical damage and chemical contamination.

Low-level output voltage, VOL: ICs of a particular family generally use a common technology, but ICs in other families, using different ec, usually have different input and output requirements, different supply voltages, and other parameters that affect the use of digital ICs.

The propagation delay time of the logic gate is taken as the average of these two delay times. Comparator as a function generator.