In computer engineering, a logic family may refer to one of two related concepts. Computer engineering (or Computer Systems Engineering) encompasses broad areas of both Electrical engineering and Computer science. A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply characteristics within a family. Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside A logic gate performs a logical operation on one or more logic inputs and produces a single logic output 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.

A "logic family" may also refer to a set of techniques used to implement logic within large scale integrated circuits such as a central processor, memory, or other complex function. Some such logic families, such as Complementary Pass-transistor Logic, use static techniques. Complementary Pass-transistor Logic refers to a CMOS-type logic family which is designed for certain advantages Other such logic families, such as domino logic, use clocked dynamic techniques to minimize size, power consumption, and delay. Domino logic is a CMOS -based evolution of the dynamic logic techniques which were based on either PMOS or NMOS Transistors It allows a rail-to-rail

Before the widespread use of integrated circuits, various solid-state and vacuum-tube logic systems were used but these were never as standardized and interoperable as the integrated circuit devices.

Contents 1 The beginning 2 ECL 3 RTL 4 DTL 5 HTL 6 TTL 7 LS TTL 8 CMOS 9 Lowering the power supply voltage 10 HC logic 11 The logic level problem 12 Improved versions 13 BiCMOS 14 Other families 15 Conclusion 16 Monolithic integrated circuit logic families table 17 External links 18 References

The beginning

The list of packaged building-block logic families can be divided into categories, listed here in rough chronological order of introduction along with their usual abbreviations:

• Diode logic (DL)
• Direct-coupled transistor logic (DCTL)
• Complementary transistor logic (CTL)
• Resistor-transistor logic (RTL)
• Resistor-capacitor transistor logic (RCTL)
• Diode-transistor logic (DTL)
• Emitter coupled logic (ECL) also known as Current-mode logic (CML)
• Transistor-transistor logic (TTL) and variants
• P-type Metal Oxide Semiconductor logic (PMOS)
• N-type Metal Oxide Semiconductor logic (NMOS)
• Complementary Metal-Oxide Semiconductor logic (CMOS)
• Bipolar Complementary Metal-Oxide Semiconductor logic (BiCMOS)
• Integrated Injection Logic (I²L)

The families (DL, RTL, DTL, and ECL) were derived from the logic circuits used in early computers, originally implemented using discrete components. Diode logic or Diode-resistor logic, is a circuit style that uses Diodes to construct Boolean Logic gates for circuits. A special type of RTL logic, a xirect-coupled transistor logic or DCTL gate is one wherein the bases of the Transistors are connected directly to inputs without Resistor–transistor logic ( RTL) is a class of Digital circuits built using Resistors as the input network and Bipolar junction transistors In electronics emitter-coupled logic, or ECL, is a Logic family in which current is steered through bipolar transistors to implement Logic Transistor–transistor logic ( TTL) is a class of Digital circuits built from Bipolar junction transistors (BJT and Resistors It is called pMOS logic uses p-type metal-oxide-semiconductor Field effect transistors (MOSFETs to implement Logic gates and other Digital circuits pMOS transistors have nMOS logic uses n-type metal-oxide-semiconductor Field effect transistors (MOSFETs to implement Logic gates and other Digital circuits nMOS transistors have Complementary metal–oxide–semiconductor ( CMOS) (pronounced "see-moss" siːmɔːs ˈsiːmɒs is a major class of Integrated circuits CMOS technology In Integrated circuit technologies BiCMOS, also called BiMOS, refers to the integration of Bipolar junction transistors and CMOS technology into Integrated Injection Logic ( IIL, I2L, or I2L) is a class of Digital circuits built with multiple collector Bipolar junction A discrete device (or discrete component) is an Electronic component with just one Circuit element, either passive ( Resistor, One example is the Philips NORbits family of logic building blocks. The 60-series NORbit is a very early form (1960's of digital logic developed by Philips that uses modules containing discrete components to build logic building blocks

The PMOS and I²L logic families were used for relatively short periods, mostly in special purpose custom LSI (Large Scale Integrated Circuits) devices and are generally considered obsolete. 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. The F14 CADC, Intel 4004, Intel 4040, and Intel 8008 microprocessors and their support chips were PMOS. The Central Air Data Computer is the integrated flight control system used in the early versions of the US Navy 's F-14 Tomcat fighter The Intel 4004 is a 4-bit Central processing unit (CPU released by Intel Corporation in 1971 The Intel 4040 Microprocessor was the successor to the Intel 4004. The Intel 8008 was an early byte-oriented Microprocessor designed and manufactured by Intel and introduced in April 1972 A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated

Of these families, only five (ECL, TTL, CMOS, NMOS, and BiCMOS) are currently still in widespread use. ECL is used for very high speed applications because of its price and power demands, while NMOS logic is mainly used in VLSI (Very Large Scale Integrated Circuits) applications such as CPUs and memory chips which fall outside of the scope of this article. Present-day "building block" logic gate ICs are based on the ECL, TTL, CMOS, and BiCMOS families.

ECL

The ECL logic family was invented by IBM as current steering logic for use in the transistorized IBM 7030 Stretch computer, where it was implemented using discrete components. In electronics emitter-coupled logic, or ECL, is a Logic family in which current is steered through bipolar transistors to implement Logic In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals The IBM 7030, also known as Stretch, was IBM 's first Transistorized Supercomputer.

The first logic family to be available in integrated circuits was emitter coupled logic, introduced by Motorola as MECL in 1962. In electronics emitter-coupled logic, or ECL, is a Logic family in which current is steered through bipolar transistors to implement Logic Motorola Inc ( is an American, multinational Fortune 100, Telecommunications company based in Schaumburg Illinois. Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. . ^[1]

RTL

The Atanasoff–Berry Computer used vacuum tube logic circuits similar to RTL. The Atanasoff–Berry Computer ( ABC) was the first electronic Digital Computing device This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. Several early transistorized computers (e. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals g. , IBM 1620) used RTL, where it was implemented using discrete components. The IBM 1620 was announced by IBM on October 21, 1959 and marketed as an inexpensive "scientific computer"

A family of simple resistor-transistor logic integrated circuits was developed at Fairchild Semiconductor for the Apollo Guidance Computer in 1962. Present day Fairchild Semiconductor International Inc is a spin-off company resulting from reconstitution of assets in National Semiconductor Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar.

Texas Instruments soon introduced its own family of RTL. Texas Instruments ( better known in the electronics industry (and popularly as TI, is an American company based in Dallas, Texas, USA

A variant with integrated capacitors, RCTL, had increased speed, but lower immunity to noise than RTL. This was made by Texas Instruments as their "51XX" series.

DTL

Diode logic goes back as far as ENIAC and was used in many early vacuum tube computers. Diode logic or Diode-resistor logic, is a circuit style that uses Diodes to construct Boolean Logic gates for circuits. ENIAC, short for Electronic Numerical Integrator And Computer, was the first general-purpose electronic Computer. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. Several early transistorized computers (e. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals g. , IBM 1401) used DTL, where it was implemented using discrete components. The IBM 1401, the first member of the IBM 1400 series, was a variable wordlength Decimal Computer that was announced by IBM on October

The first diode-transistor logic family of integrated circuits was introduced by Signetics in 1962. Signetics, once a major player in semiconductor manufacturing made a variety of devices which included Integrated circuits bipolar and MOS, the Dolby Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. DTL was also made by Fairchild and Westinghouse. Founded in 1886 as Westinghouse Electric Company and later renamed Westinghouse Electric Corporation by George Westinghouse.

A family of diode logic and diode-transistor logic integrated circuits was developed by Texas Instruments for the D-37C Minuteman II Guidance Computer in 1962, but these devices were not available to the public. Texas Instruments ( better known in the electronics industry (and popularly as TI, is an American company based in Dallas, Texas, USA The D-37C is the computer component of the all-inertial NS-17 Missile Guidance Set (MGS for accurately navigating to its target thousands of miles away The LGM-30 Minuteman is a United States nuclear Missile, a land-based Intercontinental ballistic missile (ICBM Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar.

HTL

A variant of DTL called "high threshold logic" incorporated Zener diodes to create a large offset between logic 1 and logic 0 voltage levels. A Zener diode is a type of Diode that permits current in the forward direction like a normal diode but also in the reverse direction if the voltage is larger These devices 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. ^[2]

TTL

Main article: Transistor-transistor logic

The first transistor-transistor logic family of integrated circuits was introduced by Sylvania as Sylvania Universal High–Level Logic (SUHL) in 1963. Transistor–transistor logic ( TTL) is a class of Digital circuits built from Bipolar junction transistors (BJT and Resistors It is called Year 1963 ( MCMLXIII) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. Texas Instruments introduced 5400 Series TTL family in 1964. The 7400 series of Transistor-transistor logic Integrated circuits are historically important as the first widespread family of TTL integrated circuit Year 1964 ( MCMLXIV) was a Leap year starting on Wednesday (link will display full calendar of the 1964 Gregorian calendar.

Transistor-Transistor Logic uses bipolar transistors to form its integrated circuits. A bipolar (junction transistor ( BJT) is a type of Transistor. ^[3] TTL has changed significantly over the years, with newer versions replacing the older types.

LS TTL

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. Variations on the basic TTL design are intended to reduce these effects and improve speed, power consumption, or both.

The German physicist Walter H. Schottky formulated a theory predicting the Schottky effect, which led to the Schottky diode and later Schottky transistors. Walter Hermann Schottky ( 23 July 1886, Zürich, Switzerland – 4 March 1976, Pretzfeld, West Germany The Schottky diode (named after German physicist Walter H Schottky; also known as hot carrier diode) is a Semiconductor Diode with The Schottky diode (named after German physicist Walter H Schottky; also known as hot carrier diode) is a Semiconductor Diode with A Schottky barrier is a potential barrier formed at a Metal - Semiconductor junction which has rectifying characteristics suitable for use as a Diode. Schottky transistors have a much higher switching speed than conventional transistors because the Schottky junction does not promote charge storage, leading to faster switching gates. Gates built with Schottky transistors use more power than normal TTL and switch faster. With low power Schottky circuits, internal resistance values were increased to reduce power consumption and increase switching speed over the original version. The introduction of Advanced Low Power(ALS) further increased speed and reduced power consumption. A faster logic family called 'Fast TTL' (F) was also introduced that was faster than normal Schottky TTL.

CMOS

CMOS gates use a complementary pair of FETs (a N-MOS and a P-MOS FET). The field-effect transistor (FET is a type of Transistor that relies on an Electric field to control the shape and hence the conductivity of a 'channel' Since the initial devices used metal layers for gate contacts, they were called CMOS (Complementary Metal Oxide Semiconductor logic). Complementary metal–oxide–semiconductor ( CMOS) (pronounced "see-moss" siːmɔːs ˈsiːmɒs is a major class of Integrated circuits CMOS technology

In contrast to TTL logic, CMOS uses almost no power in the static state (i. e. when inputs are not changing). A CMOS gate draws no current other than leakage when in a steady 1 or 0 state. When the gate switches states, current is drawn from the power supply to charge the stray capacitance at the output of the gate. This means that current draw of CMOS devices increases with clock speed.

The first CMOS logic family of integrated circuits was introduced by RCA as CD4000 COS/MOS, the 4000 series, in 1968. RCA Corporation, founded as Radio Corporation of America, was an electronics company in existence from 1919 to 1986 The 4000 series is a family of industry standard Integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar. Initially CMOS logic was slower than LS-TTL; 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. 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.

With this technology the required silicon area for implementing such digital CMOS functions has rapidly shrunk. Nowadays, the modern VLSI technology, allowing for incorporating many millions of basic logic operations onto one single silicon chip, almost exclusively exploits this CMOS technology. The extremely small capacitance of the on chip wiring, as well as its length compared to a PCB, combined with the absence of the delay created by the required I/O-cells of all separate gate chips, caused an increase in performance by several orders of magnitude. On chip clock rates as high as 4 GHz have become common, approximately 1000 times faster than the technology by 1970.

Lowering the power supply voltage

One very important feature of CMOS chips is that they work with a broader range of power supply voltages. While TTL ICs all require a power supply voltage of 5V (+/- 0. Power supply is a reference to a source of Electrical power. A device or system that supplies Electrical or other types of Energy to an output load Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical 5V), CMOS works with a wider range of power supply voltage – usually anywhere from 3 to 15V. Lowering the supply voltage reduces the current required to charge stray capacitance, and so reduces the current drawn by complex microprocessors. This in turn reduces the heat dissipation of the processor. By lowering the power supply from 5V to 3. 3V, switching power was reduced by almost 60 percent (power dissipation is proportional to the square of the supply voltage). Newer CPUs have lowered their power supply voltages further.

HC logic

Because of the incompatibility of the CD4000 series of chips with the previous TTL family, a new standard emerged which combined the best of the TTL family with the advantages of the CD4000 family. It was known as the 74HC (High performance silicon gate) family of devices and used the pinout of the 74LS family with an improved version of CMOS technology inside the chip. Pinout is a term used in Electronics to describe how an Electrical connector is wired It could be used both with logic devices which used 3. 3V power supplies (and thus 3. 3V logic levels), and with devices that used 5V power supplies and TTL logic levels. Digital electronics are Electronics systems that use Digital signals Digital electronics are representations of Boolean algebra also see

The logic level problem

Interconnecting any two logic families often required special techniques such as additional pull-up resistors, or 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.

TTL logic levels are different from those of CMOS – generally a TTL output does not rise high enough to be reliably recognized as a logic 1 by a CMOS input. This problem was solved by the invention of the 74HCT family of devices that uses CMOS technology but TTL input logic levels. These devices only work with a 5V power supply. They form a replacement for TTL logic, although HCT is slower than original TTL (HC logic has about the same speed as original TTL).

Improved versions

With HC and HCT logic and LS-TTL logic competing in the market it became clear that further improvements were needed to create the 'ideal' logic device that combined high speed, with low power dissipation and compatibility with older logic families. A whole range of newer families has emerged that use CMOS technology. A short list of the most important family designators of these newer devices includes:

• LV logic (lower supply voltage)
• LVT logic (lower supply voltage while retaining TTL logic levels)
• ALVT logic (an 'advanced' version of LVT logic)

But there are many others including AC/ACT logic, AHC/AHCT logic, ALVC logic, AUC logic, AVC logic, CBT logic, CBTLV logic, FCT logic, LVC logic and LVC logic.

BiCMOS

One major improvement was to combine CMOS inputs and TTL drivers to form of a new type of logic devices called BiCMOS logic, of which the LVT and ALVT logic families are the most important. In Integrated circuit technologies BiCMOS, also called BiMOS, refers to the integration of Bipolar junction transistors and CMOS technology into The BiCMOS family has many members, including ABT logic, ALB logic, ALVT logic, BCT logic and LVT logic.

Other families

Other circuit families include:

• Complementary Pass-transistor Logic (CPL)
• Cascode Voltage Switch Logic (CVSL)

These are generally used "on-chip" and are not delivered as building-block medium-scale or small-scale integrated circuits. Complementary Pass-transistor Logic refers to a CMOS-type logic family which is designed for certain advantages Cascode Voltage Switch Logic refers to a CMOS-type logic family which is designed for certain advantages

Conclusion

At the moment the most common logic families still are the LS-TTL and the HC and HCT families, although BCT logic also is starting to become popular. Low voltage logic families are becoming more important, with AHC logic gaining popularity. Because not every manufacturer supports every logic family, several families of logic circuits will continue to be used.

Monolithic integrated circuit logic families table

The following logic families would either have been used to build up systems from functional blocks such as flip-flops, counters, and gates, or else would be used as "glue" logic to interconnect very-large scale integration devices such as memory and processors. Not shown are some early obscure logic families from the early 1960's such as direct-coupled transistor logic, which did not become widely available.

"Propagation delay" is the time taken for a two-input NAND gate to produce a result after a change of state at its inputs. "Toggle speed" represents the fastest speed at which a J-K flip flop could operate. "Power per gate" is for an individual 2-input NAND gate; usually there would be more than one gate per IC package. Values are very typical and would vary slightly depending on application conditions, manufacturer, temperature, and particular type of logic circuit. "Introduction year" is when at least some of the devices of the family were available in volume for civilian uses. Some military applications pre-dated civilian use. ^{[4] [5]}

Family	Description	Propagation delay (ns)	Toggle speed (MHz)	Power per gate @1 MHz (mW)	Typical supply voltage V (range)	Introduction year	Remarks
RTL	Resistor-transistor logic	__	4	10	3. Resistor–transistor logic ( RTL) is a class of Digital circuits built using Resistors as the input network and Bipolar junction transistors 3	1963	the first CPU built from integrated circuits (the AGC) used RTL.
DTL	Diode-transistor logic	__	__	10	5	1962	Introduced by Signetics, Fairchild 930 line became industry standard in 1964
CMOS	AC/ACT	3	125	0. 5	3. 3 or 5 (2-6 or 4. 5 to 5. 5)	1985	ACT has TTL Compatible levels
CMOS	HC/HCT	9	30	0. 5	5 (2-6)	1982	HCT has TTL compatible levels
CMOS	4000B/74C	30	5	1. 2	10V (3-18)	1970	Approximately half speed and power at 5 volts
TTL	Original series	10	25	10	5 (4. 75-5. 25)	1964	Several manufacturers
TTL	L	33	3	1	5 (4. 75-5. 25)	1964	Low power
TTL	H	6	43	22	5 (4. 75-5. 25)	1964	High speed
TTL	S	3	110	19	5 (4. 75-5. 25)	1969	Schottky high speed
TTL	LS	10	33	2	5 (4. 75-5. 25)	1976	Low power Schotky high speed
TTL	ALS	4	34	1. 3	5 (4. 5-5. 5)	1976	Advanced Low power Schottky
TTL	F	3. 5	100	5. 4	5 (4. 75-5. 25)	1979	Fast
TTL	AS	2	105	8	5 (4. 5-5. 5)	1980	Advanced Schottky
TTL	AS	2	105	8	5 (4. 5-5. 5)	1980	Advanced Schottky
ECL	ECL III	1	500	60	-5. 2(-5. 19 - -5. 21)	1968	Improved ECL
ECL	MECL I	8		31	-5. 2	1962	first integrated logic circuit commercially produced
ECL	ECL 10K	2	125	25	-5. 2(-5. 19 - -5. 21)	1971	Motorola
ECL	ECL 100K	. 75	350	40	-4. 5(-4. 2 - -5. 2)	1981
ECL	ECL 100KH	1	250	25	-5. 2(-4. 9 - -5. 5)	1981
ECL	ECL 100K	. 75	350	40	-4. 5(-4. 2 - -5. 2)	1981

External links

• What Computers are Made From

References

• The Engineering Staff, The TTL Data Book for Design Engineers, 1st Ed. , Texas Instruments, Dallas Texas, 1973, no ISBN
• H. P. Westman (ed), Reference Data for Radio Engineers 5th Edition, Howard W. Sams & Co. , Indianapolis, 1968, no ISBN, Library of Congress Card 43-14665

---

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic