Analog chip
Encyclopedia
An analog chip is a set of miniature electronic analog circuits formed on a single piece of semiconductor
material.
and current
at specified points in the circuits of an analog chips vary continuously in time. In contrast, digital
chips only use and create voltages or currents at discrete levels, with no intermediate values. In addition to Transistor
s, analog chips often have a larger number of passive elements (Inductor
/Capacitor
s/Resistor
s) than digital chips typically do. Inductors tend to be avoided because of their large size. It was one of those fortunate discoveries that a transistor and capacitor together can do the work of an inductor. When this trick is used in a CFL
, you get an electronic ballast.
Analog chips may also contain digital logic elements to replace some analog functions, or to allow the chip to communicate with a microprocessor
. For this reason and since logic is commonly implemented using CMOS
technology, these chips use BiCMOS
processes by companies such as Freescale, Texas Instruments
, STMicroelectronics
and others. This is known as mixed signal processing and allows a designer to incorporate more functions in the chip. Some of the benefits include load protection, reduced pats count and higher reliability.
Pure analog chips in information processing have been mostly replaced with digital chips. Analog chips are still required for wideband signals on account of sampling rate requirements, high power applications and at the transducer
interfaces. Research and industry in the field continues to grow and prosper. Some examples of long-lived and well-known analog chips are the 741 Operational Amplifier
, and the 555 timer
.
Power supply
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 PMICs are important elements of those systems.
Important basic building blocks of analog chip design include:
All the above circuit building blocks can be implemented using Bipolar technology as well as Metal-Oxide-Silicon(MOS) technology. MOS Band gap
references use lateral (poor) bipolar transistors for their functioning.
People who have specialized in this field include Bob Widlar
, Bob Pease
, Hans R. Camenzind
, George Erdi, and Barry Gilbert
among others.
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
material.
Description
The voltageVoltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
and current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
at specified points in the circuits of an analog chips vary continuously in time. In contrast, digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
chips only use and create voltages or currents at discrete levels, with no intermediate values. In addition to Transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
s, analog chips often have a larger number of passive elements (Inductor
Inductor
An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
/Capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s/Resistor
Resistor
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...
s) than digital chips typically do. Inductors tend to be avoided because of their large size. It was one of those fortunate discoveries that a transistor and capacitor together can do the work of an inductor. When this trick is used in a CFL
Compact fluorescent lamp
A compact fluorescent lamp , also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent lamp; some types fit into light fixtures formerly used for incandescent lamps...
, you get an electronic ballast.
Analog chips may also contain digital logic elements to replace some analog functions, or to allow the chip to communicate with a microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
. For this reason and since logic is commonly implemented using CMOS
CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
technology, these chips use BiCMOS
BiCMOS
BiCMOS is an evolved semiconductor technology that integrates two formerly separate semiconductor technologies - those of the analog bipolar junction transistor and the digital CMOS transistor - in a single integrated circuit device....
processes by companies such as Freescale, Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
, STMicroelectronics
STMicroelectronics
STMicroelectronics is an Italian-French electronics and semiconductor manufacturer headquartered in Geneva, Switzerland.While STMicroelectronics corporate headquarters and the headquarters for EMEA region are based in Geneva, the holding company, STMicroelectronics N.V. is registered in Amsterdam,...
and others. This is known as mixed signal processing and allows a designer to incorporate more functions in the chip. Some of the benefits include load protection, reduced pats count and higher reliability.
Pure analog chips in information processing have been mostly replaced with digital chips. Analog chips are still required for wideband signals on account of sampling rate requirements, high power applications and at the transducer
Transducer
A transducer is a device that converts one type of energy to another. Energy types include electrical, mechanical, electromagnetic , chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a...
interfaces. Research and industry in the field continues to grow and prosper. Some examples of long-lived and well-known analog chips are the 741 Operational Amplifier
Operational amplifier
An operational amplifier is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output...
, and the 555 timer
555 timer IC
The 555 timer IC is an integrated circuit used in a variety of timer, pulse generation and oscillator applications. The part is still in widespread use, thanks to its ease of use, low price and good stability. , it was estimated that 1 billion units are manufactured every year.- Design :The IC...
.
Power supply
Power supply
A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
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 PMICs are important elements of those systems.
Important basic building blocks of analog chip design include:
- current sources
- current mirrorCurrent mirrorA current mirror is a circuit designed to copy a 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 'copied' can be, and sometimes is, a varying signal current...
s - differential amplifierDifferential amplifierA differential amplifier is a type of electronic amplifier that amplifies the difference between two voltages but does not amplify the particular voltages.- Theory :Many electronic devices use differential amplifiers internally....
- bandgap referencesVoltage referenceA voltage reference is an electronic device that produces a fixed voltage irrespective of the loading on the device, power supply variations, temperature changes, and the passage of time. Voltage references are used in power supply voltage regulators, analog-to-digital converters and...
.
All the above circuit building blocks can be implemented using Bipolar technology as well as Metal-Oxide-Silicon(MOS) technology. MOS Band gap
Band gap
In solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference between the top of the valence band and the...
references use lateral (poor) bipolar transistors for their functioning.
People who have specialized in this field include Bob Widlar
Bob Widlar
Robert John Widlar was an American electronic engineer and a pioneer of linear integrated circuit design. Widlar invented the basic building blocks of linear ICs like the Widlar current source, the Widlar bandgap voltage reference and the Widlar output stage...
, Bob Pease
Bob Pease
Robert Allen Pease was an analog integrated circuit design expert and technical author. He designed several very successful "best-seller" integrated circuits, many of them in continuous production for multiple decades...
, Hans R. Camenzind
Hans R. Camenzind
Hans R. Camenzind is an electronics engineer best known for inventing the 555 timer IC in 1970. He has also acquired 20 US patents, written numerous books and technical articles, and lectured at the University of Santa Clara.He received an MSEE from Northeastern University and an MBA from the...
, George Erdi, and Barry Gilbert
Barry Gilbert
.Barry Gilbert is a fictional Toronto police homicide detective in the books by Canadian science fiction author Scott Mackay....
among others.