A linear integrated circuit or analog chip is a set of miniature electronic

analog circuit Analogue electronics () are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two levels. The term ''analogue'' describes the proportional relationship between a signal ...

s formed on a single piece of

semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

material.

Description

The

voltage Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...

and current at specified points in the circuits of analog chips vary continuously over time. In contrast,

digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

chips only assign meaning to voltages or currents at discrete levels. In addition to

transistor A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...

s, analog chips often include a larger number of passive elements (

capacitor In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...

resistor A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active e ...

s, and

inductor An inductor, also called a coil, choke, or reactor, is a Passivity (engineering), passive two-terminal electronic component, electrical component that stores energy in a magnetic field when an electric current flows through it. An inductor typic ...

s) than digital chips. Inductors tend to be avoided because of their large physical size, and difficulties incorporating them into monolithic semiconductor ICs. Certain circuits such as

gyrator A gyrator is a passivity (engineering), passive, Linear circuit, linear, lossless, two-port network, two-port electrical lumped-element model, network element proposed in 1948 by Bernard D. H. Tellegen as a hypothetical fifth linear element after t ...

s can often act as equivalents of inductors, while constructed only from transistors and capacitors. Analog chips may also contain digital logic elements to replace some analog functions, or to allow the chip to communicate with a

microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...

. For this reason, and since logic is commonly implemented using

CMOS Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss ", , ) is a type of MOSFET, metal–oxide–semiconductor field-effect transistor (MOSFET) semiconductor device fabrication, fabrication process that uses complementary an ...

technology, these chips typically use

BiCMOS Bipolar CMOS (BiCMOS) is a semiconductor technology that integrates two semiconductor technologies, those of the bipolar junction transistor and the CMOS (complementary metal–oxide–semiconductor) logic gate, into a single integrated circuit. ...

processes, as implemented by companies such as

Freescale Freescale Semiconductor, Inc. was an American semiconductor manufacturer. It was created by the divestiture of the Semiconductor Products Sector of Motorola in 2004. Freescale focused their integrated circuit products on the automotive, embedde ...

Texas Instruments Texas Instruments Incorporated (TI) is an American multinational semiconductor company headquartered in Dallas, Texas. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog ...

STMicroelectronics STMicroelectronics Naamloze vennootschap, NV (commonly referred to as ST or STMicro) is a European multinational corporation, multinational semiconductor contract manufacturing and design company. It is the largest of such companies in Europe. ...

, and others. This is known as "mixed signal processing", and allows a designer to incorporate more functions into a single chip. Some of the benefits of this mixed technology include load protection, reduced parts count, and higher reliability.Information Freescale website, Mar 28th 2010
About Freescale Analog Products
/ref> Purely analog chips in information processing have been mostly replaced with digital chips. Analog chips are still required for wideband signals, high-power applications, and

transducer A transducer is a device that Energy transformation, converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, M ...

interfaces. Research and industry in this specialty continues to grow and prosper. Some examples of long-lived and well-known analog chips are the 741 operational amplifier, and the

555 timer IC The 555 timer IC is an integrated circuit used in a variety of timer, delay, pulse generation, and Electronic oscillator, oscillator applications. It is one of the most popular timing ICs due to its flexibility and price. Derivatives provide two ...

Power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, electric current, current, and frequency to power ...

chips are also considered to be analog chips. Their main purpose is to produce a well-regulated output voltage supply for other chips in the system. Since all electronic systems require electrical power, power supply ICs ( power management integrated circuits, PMIC) are important elements of those systems. Important basic building blocks of analog chip design include: *

current source A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. A current source is the dual of a voltage source. The term ''current sink'' is sometimes used for sources fed ...

current mirror A current mirror is a circuit designed to copy a electric current, current through one active device by controlling the current in another active device of a circuit, keeping the output current constant regardless of loading. The current being "co ...

differential amplifier A differential amplifier is a type of electronic amplifier that amplifies the difference between two input voltages but suppresses any voltage common to the two inputs. It is an analog circuit with two inputs V_\text^- and V_\text^+ and one outp ...

* voltage reference, bandgap voltage reference All the above circuit building blocks can be implemented using bipolar technology as well as metal-oxide-silicon (MOS) technology. MOS

band gap In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to t ...

references use lateral bipolar transistors for their functioning. People who have specialized in this field include Bob Widlar, Bob Pease, Hans Camenzind, George Erdi, Jim Williams, and Barrie Gilbert, among others.

References

Intelligent Power and Sensing TechnologiesCMOS Oscillators (AN-118)CMOS Schmitt Trigger—A Uniquely Versatile Design Component (AN-140)HCMOS Crystal Oscillators (AN-340)

Description

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References

Further reading