VLSI Basics

 An integrated circuit (IC) is a small semiconductors-based electronic device consisting of fabricated transistors, resistors, and capacitors. Integrated circuits are the building blocks of most electronic devices and equipment .

There are two main advantages of ICs over discrete circuits: cost and performance. Cost is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, much less material is used to construct a packaged IC die than a discrete circuit. Performance is high since the components switch quickly and consume little power (compared to their discrete counterparts) because the components are small and positioned close together. As of 2006, chip areas range from a few square millimeters to around 350 mm2, with up to 1 million transistors per mm.

Moore’s Law:

The level of integration of silicon technology as measured in terms of the number of devices per IC Semiconductor industry has followed this prediction with surprising accuracy. 

“The number of transistors on an integrated circuit will double every 18 months”.

IC Technology: 

• Speed / Power performance of available technologies.

The scale of Integration:

  Small scale integration(SSI) --1960 The technology was developed by integrating the number of transistors of 1-100 on a single chip. Ex: Gates, flip-flops, op-amps. 

 Medium-scale integration(MSI) --1967 The technology was developed by integrating the number of transistors of 100- 1000 on a single chip. Ex: Counters, MUX, adders, 4-bit microprocessors. 

 Large scale integration(LSI) --1972 The technology was developed by integrating the number of transistors of 1000- 10000 on a single chip. Ex:8-bit microprocessors, ROM, RAM. 

 Very large scale integration(VLSI) -1978 The technology was developed by integrating the number of transistors of 10000- 1Million on a single chip. Ex:16-32 bit microprocessors, peripherals, complimentary high MOS.