What is a tiny sheet of silicon containing an entire circuit with many different components?

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History and evolution of integrated circuits
Modern integrated circuits: Design and construction
Types of integrated circuits
Microprocessors and ICs

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integrated circuit (IC), also called microelectronic circuit, microchip, or chip, an assembly of electronic components, fabricated as a single unit, in which miniaturized active devices (e.g., transistors and diodes) and passive devices (e.g., capacitors and resistors) and their interconnections are built up on a thin substrate of semiconductor material (typically silicon). The resulting circuit is thus a small monolithic “chip,” which may be as small as a few square centimetres or only a few square millimetres. The individual circuit components are generally microscopic in size.

transistor

Integrated circuits have their origin in the invention of the transistor in 1947 by William B. Shockley and his team at the American Telephone and Telegraph Company’s Bell Laboratories. Shockley’s team (including John Bardeen and Walter H. Brattain) found that, under the right circumstances, electrons would form a barrier at the surface of certain crystals, and they learned to control the flow of electricity through the crystal by manipulating this barrier. Controlling electron flow through a crystal allowed the team to create a device that could perform certain electrical operations, such as signal amplification, that were previously done by vacuum tubes. They named this device a transistor, from a combination of the words transfer and resistor. The study of methods of creating electronic devices using solid materials became known as solid-state electronics. Solid-state devices proved to be much sturdier, easier to work with, more reliable, much smaller, and less expensive than vacuum tubes. Using the same principles and materials, engineers soon learned to create other electrical components, such as resistors and capacitors. Now that electrical devices could be made so small, the largest part of a circuit was the awkward wiring between the devices.

In 1958 Jack Kilby of Texas Instruments, Inc., and Robert Noyce of Fairchild Semiconductor Corporation independently thought of a way to reduce circuit size further. They laid very thin paths of metal (usually aluminum or copper) directly on the same piece of material as their devices. These small paths acted as wires. With this technique an entire circuit could be “integrated” on a single piece of solid material and an integrated circuit (IC) thus created. ICs can contain hundreds of thousands of individual transistors on a single piece of material the size of a pea. Working with that many vacuum tubes would have been unrealistically awkward and expensive. The invention of the integrated circuit made technologies of the Information Age feasible. ICs are now used extensively in all walks of life, from cars to toasters to amusement park rides.

Analog, or linear, circuits typically use only a few components and are thus some of the simplest types of ICs. Generally, analog circuits are connected to devices that collect signals from the environment or send signals back to the environment. For example, a microphone converts fluctuating vocal sounds into an electrical signal of varying voltage. An analog circuit then modifies the signal in some useful way—such as amplifying it or filtering it of undesirable noise. Such a signal might then be fed back to a loudspeaker, which would reproduce the tones originally picked up by the microphone. Another typical use for an analog circuit is to control some device in response to continual changes in the environment. For example, a temperature sensor sends a varying signal to a thermostat, which can be programmed to turn an air conditioner, heater, or oven on and off once the signal has reached a certain value.

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logic circuit

A digital circuit, on the other hand, is designed to accept only voltages of specific given values. A circuit that uses only two states is known as a binary circuit. Circuit design with binary quantities, “on” and “off” representing 1 and 0 (i.e., true and false), uses the logic of Boolean algebra. (Arithmetic is also performed in the binary number system employing Boolean algebra.) These basic elements are combined in the design of ICs for digital computers and associated devices to perform the desired functions.

An integrated circuit (IC), sometimes called a chip, microchip or microelectronic circuit, is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, diodes and transistors are fabricated. An IC can function as an amplifier, oscillator, timer, counter, logic gate, computer memory, microcontroller or microprocessor.

An IC is the fundamental building block of all modern electronic devices. As the name suggests, it's an integrated system of multiple miniaturized and interconnected components embedded into a thin substrate of semiconductor material (usually silicon crystal).

Microcontrollers are integrated circuits that govern specific operations in embedded systems, consisting of a processor, memory and input/output peripherals on a chip. This image shows a Microchip Technology ATtiny817 microcontroller.

A single IC could contain thousands or millions of:

transistors
resistors
capacitors
diodes

Additional components may also reside on it, all interconnected through a complex web of semiconductor wafers, silicon, copper and other materials. Size-wise, each component is small, usually microscopic. The resulting circuit, a monolithic chip, is also tiny -- often just enough to occupy a few square millimeters or centimeters of space.

One common example of a modern-day IC is the computer processor, which typically contains millions or billions of transistors, capacitors, logic gates, etc., connected together to form a complex digital circuit. Although the processor is an IC, not all ICs are processors.

History and evolution of integrated circuits

The invention of the transistor -- a combination of the words transfer and resistor -- in 1947 set the stage for the modern computer age.

In the early days, each transistor came in a separate plastic package, and each circuit consisted of discrete transistors, capacitors and resistors. Due to the large size of these components, early ICs were only capable of holding a few of them -- wired together -- on the circuit board.

Over time, the development of solid-state electronics made it easier to reduce the size of components.

In the late 1950s, inventors Jack Kilby of Texas Instruments, Inc., and Robert Noyce of Fairchild Semiconductor Corporation found ways to lay thin paths of metal on devices and have them function as wires. Their solution to the problem of wiring between small electrical devices was the beginning of the development of the modern IC.

Integrated circuits have undergone several generations of advancements according to their design assembly, size and number of components per chip.

Modern integrated circuits: Design and construction

For the past half-century, ICs have progressed enormously with faster speeds, greater capacity and smaller sizes.

Compared to the early days, today's ICs are unbelievably complex, capable of holding billions of transistors and other components on a single small piece of material. The modern IC is all one piece, with individual components embedded directly into the silicon crystal, rather than simply mounted on it.

An IC relies on multiple levels of abstraction. The semiconductor wafer that makes up the IC is fragile and contains numerous intricate connections between its many layers. A combination of these wafers is known as a die.

With millions or billions of components on one single chip, it's not possible to position and connect each component individually. Dies are too small to solder and connect to. Instead, designers use a special-purpose programming language to create small circuit elements and combine them to progressively increase the size and density of components on the chip to meet application requirements.

The ICs are "packaged" to turn the delicate and tiny die into a black chip that now forms the basis of hundreds of devices, including:

Code-named Ice Lake, Intel's new 3rd generation Xeon Scalable processor.

Types of integrated circuits

ICs can be linear (analog), digital or some combination of the two, depending on their intended application.

Analog or linear ICs have a continuously variable output, depending on the input signal level. In theory, such ICs can attain an infinite number of states. With this IC type, the output signal level is a linear function of the input signal level. Ideally, when the instantaneous output is graphed against the instantaneous input, the plot appears as a straight line.

Analog ICs usually use only a few components and are quite simple.

Linear ICs are used as audio-frequency (AF) and radio-frequency (RF) amplifiers. The operational amplifier (op amp) is a common device in these applications. Another common application of an analog IC is the temperature sensor. Linear ICs can be programmed to turn various devices on or off once a signal reaches a particular value. These include:

air conditioners
heaters
ovens

Unlike analog ICs, digital ICs don't operate over a continuous range of signal amplitudes. Rather, they operate at only a few defined (discrete) levels or states. The fundamental building blocks of digital ICs are logic gates, which work with binary data, i.e. signals that have only two different states, called low (logic 0) and high (logic 1).

Digital ICs are now used in an increasing number of applications, including:

computers
enterprise networks
modems
frequency counters

A mixed IC incorporates both analog and digital design principles. It may function as a:

digital-to-analog converter
analog-to-digital converter
clock/timer IC

Microprocessors and ICs

The microprocessor is the most complicated type of IC, capable of performing billions of operations per second. In a computing device, a microprocessor contains the central processing unit (CPU) which runs a computer or the graphics processing unit (GPU), which specializes in the rendering images and video. A single microprocessor contains billions of interconnected transistors, each of which performs a specific logic function based on instructions from the clock.

When the clock changes state, the transistors perform the logic functions (e.g., calculations) they are programmed to perform. The clock's frequency determines the speed of these functions.

Today's CPUs and GPUs are multicore, meaning their integrated circuitry has two or more processors to process multiple tasks simultaneously, enhance performance and lower power consumption. The former can have several cores, the latter thousands.

Microprocessors also contain different kinds of predetermined memory locations or registers that store information:

Permanent register: stores preprogrammed instructions for various operations.
Temporary register: stores numbers to be operated on, and the results of an operation.
Counter: contains the memory address of the next instruction.
Stack pointer: contains the address of the last instruction put into the stack memory.
Memory address register: contains the location (address) of the data to be worked on.

The IC made our lives infinitely better. A modern laptop computer is thousands of times more powerful and about 100 times smaller than the first computer developed in the 1940s. The ENIAC was about as large as three to four double-decker buses and ran on 18,000 vacuum tubes.

To say we've come a long way is an understatement as massive as the ENIAC. The IC was key to that progress.