Integrated Circuit

Integrated Circuit

What is IC?

Integrated circuit are assembly of electronic components, fabricated as a single unit. They are also called as chip or microchip. Almost every kind of electronic circuits can be integrated together as a single unit, for example amplifier, oscillator, timer, counter, computer memory, microprocessor etc.  Since, transistors are very small, a large number of them can be integrated together into a single package. When circuits are integrated together, power consumption will increase along with the number of components. Integrated circuits generate heat, so in some versions, they have a metal tag to which heat sink can be attached to dissipate heat. Now technology has advanced so much that, even billions of transistors and other electronic components can be integrated together into a single chip. 

Classification of Integrated Circuit

Classification of Integrated Circuit By structure

1. Monolithic Integrated Circuit

In this type of IC, the components will be fabricated within the wafer inseparably.

2. Thin and Thick Film IC

The method of deposition of film is the major difference between the thin and thick film ICs.  Thin film ICs are made by the deposition of conducting material through a mask on a substrate. Vacuum evaporation and Cathode sputtering is the technique used for depositing the desired material on the substrate. Thick Film ICs uses screen print methods to make the circuit pattern on the substrate surface.

3. Hybrid IC

These are formed by the interconnection of many single chips. It uses the combination of monolithic and thick/thin film techniques.

Another classification of integrated circuits  based on their input and output characteristics.

(a). Analog integrated circuits

                Analog integrated circuits or linear integrated circuits can have infinite number of possible operating states. Output of Analog integrated circuit can have continuously variable inputs or outputs. They are widely used in audio applications. Amplifiers, Oscillators, Timers, Analog to digital convertors are the most commonly used linear integrated circuits.

(b). Digital integrated circuits

                It is a class of integrated circuits that can process digital information.  Digital integrated circuit can handle only two states, logic zero and logic one.

Generations of Integrated Circuit

With the growth of technology, number of electronic components that can be integrated together in a single chip has increased dramatically. Taking transistor count as reference, integrated circuits are divided into few categories.  

Small Scale Integration (SSI)

• Small scale integration is the first generation integrated circuits with a limited transistor count of about hundred components per chip. It was first used in aerospace projects like Minuteman missile and the Apollo program.

Medium Scale Integration (MSI)

• Medium scale integration is little more advanced than Small scale integration. Its component’s density ranges from hundred to three thousand components per chip.

Large Scale Integration (LSI)

• In large scale integration, the component density has increased further. It ranges from three thousand to one lakh components per chip.

Very Large Scale Integration (VLSI)

• Component density in very large scale integration is from one lakh to ten lakh components per chip.

Ultra Large Scale Integration (ULSI)

• Ultra large scale integration is most advanced technology in the fabrication of integrated circuits. More than ten lakh components are integrated together in a single chip.

IC Terminology

• Chip/Die - small part of the wafer on which the integrated circuit will be fabricated.
• Wafer – a semiconductor material in rectangular or circular shape where large number of the ICs are been fabricated.
• Encapsulations – Put a cap over the integrated circuit and seal it in an inert atmosphere.
• Bonding – Attach wires to IC.?

Advantages of Integrated Circuit

• Small Size
• Small Weight
• Less cost
• Better Reliability.
• Good for small signal operation.
• Less power
• Better replacement.

Disadvantages of Integrated Circuit

• Cannot withstand excess heat.
• Handle less power.
• Function at low voltages.