Integrated Circuits (ICs) are the building blocks of modern electronics. Anything from a wristwatch to a roller coaster has Integrated Circuits in it. ICs have changed electronics as we see it. The functionality of computers, cellular phones, home appliances, industrial control systems, transport systems, music systems, and medical electronics have improved vastly owing to Integrated Circuits.
Any electronic circuit is built using numerous transistors, capacitors, resistors, diodes, and connecting wires on a circuit board. An Integrated Circuit is a compact version of the same circuit fabricated on a single chip, which only measures a few square millimeters.
TYPES OF INTEGRATED CIRCUITS
Types of ICs based on chip size
This classification of ICs depends on the number of active devices (transistors) available on a single chip.
- Small Scale Integration (SSI) – Less than 100 active devices on a chip. SSI chips are built with resistors, diodes, and bipolar junction transistors (BJTs).
- Medium Scale Integration (MSI) – 100 to 1000 active devices on a chip. MSI chips are built with BJTs and enhancement mode MOSFETS.
- Large Scale Integration (LSI) – 1000 to 100,000 active devices on a chip. LSI chips are built with MOS transistors.
- Very Large Scale Integration (VLSI) – More than 100,000 active devices on a chip.
- Ultra Large Scale Integration (ULSI) – More than one million active devices on a chip.
Most modern ICs use VLSI technology, while ULSI is a recent development used in the Intel 486 and Pentium microprocessors.
Types of ICs based on manufacturing technique
This classification is based on the manufacturing technique of ICs.
- Monolithic ICs – All the components (active & passive) are manufactured on a single (mono) chip. These are the most commonly used ICs. Low power applications like AM receivers, TV circuits, computer circuits, voltage regulators, and amplifiers use Monolithic ICs.
- Thick-thin film ICs – Used for high power applications, only passive components are integrated on the chip. The passive components have to be connected as discrete circuits externally.
- Hybrid ICs – Hybrid ICs are a combination of two or more monolithic ICs or a combination of monolithic ICs with thick-thin film ICs
Types of ICs based on functionality
- Digital ICs – These ICs accept and process digital inputs, 0’s and 1’s only (low & high or on and off), following binary logic. This functionality makes these ICs apt for digital computers and the associated circuits like Microprocessors, Microcontrollers, and Digital Signal Processors (DSPs).
- Analog ICs – These ICs accept and process analog signals, and are apt for systems designed for real-time signal processing. Operational Amplifiers (OP-AMP), NE 555 Timers, and sensor circuits are good examples. These ICs are used in thermostats, air conditioners, heaters, and other digital home appliances.
- Mixed signal ICs – Digital ICs and Analog ICs are combined together on a single chip to form the mixed signal ICs. These ICs are used in data acquisition.
APPLICATION – SPECIFIC ICs
An Application – Specific IC (ASIC) performs only the task it is designed and built for, and cannot be reconfigured like a microprocessor. There are three different types of ASICs: Full-custom ASICs, Semi-custom ASICs, and Programmable ASICs. Some features of the Semi-custom ASICs can be modified during the manufacturing process. Programmable ASICs are Programmable Logic Devices (PLDs) and Field Programmable Gate Arrays (FPGAs). ASICs are used in digital voice recorders, satellites, medical applications, and research.
RADIO – FREQUENCY ICs
Radio – Frequency ICs (RFICs) are analog ICs that function in the frequency range of 3,000 Hz to 2.4 billion Hz. The applications of RFICs are in mobile phones and wireless devices.
The Monolithic Microwave IC (MMIC) is a type of RFIC, which functions in the frequency range of 2 GHz to 100 GHz (microwave frequencies). Silicon as an IC material shows a lot of resistance in circuits working on microwave frequencies, so compound materials like Gallium Arsenide (GaAs) and Gallium Nitride (GaN) are often used for MMICs.
MMICs are the ICs of choice for radar systems, satellite communications, power amplifiers, and instrumentation applications. The most important applications of MMICs are in defense, aerospace, electronic warfare, and military communications.