IC TECHNOLOGY in VLSI
The invention of vacuum tubes and associated electronic circuits has led to the endless development of electronics, which is known as vacuum tube electronics. Afterward the evolution of solid state devices and consequent development of integrated circuits are responsible for the present status of communication, computing and instrumentation.
- The first vaccum tube diode was invented by John Ambrase Fleming in 1904.
- The vaccum triode was invented by lee de forest in 1906.
Integrated circuits were made possible by experimental discoveries which showed that semiconductor devices could perform the functions of vacuum tubes and by mid-20th-century technology advancements in semiconductor device fabrication .
The integration of large numbers of tiny transistors into a small chip was an enormous improvement over the manual assembly of circuits using electronic components.
The integrated circuits mass production capability, reliability, and building-block approach to circuit design ensured the rapid adoption of standardized ICs in place of designs using discrete transistors.
An integrated circuit (IC) is a small semiconductor-based electronic device consisting of fabricated transistors, resistors and capacitors. Integrated circuits are the building blocks of most electronic devices and equipment. An integrated circuit is also known as a chip or microchip.
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:
- Gordon E. Moore – Chairman Emeritus of Intel Corporation.
- 1965 – observed trends in industry of transistors on ICs vs release dates.
- Noticed number of transistors doubling with release of each new IC generation.
- Release dates (separate generations) were all 18-24 months apart.
"The number of transistors on an integrated circuit will double every 18 months"
The level of integration of silicon technology as measured in terms of number of devices per IC Semiconductor industry has followed this prediction with surprising accuracy.
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.
- Ultra large scale integration(ULSI) The technology was developed by integrating the number of transistors of 1Million10 Millions on a single chip. Ex: special purpose processors.
- Giant scale integration(GSI) The technology was developed by integrating the number of transistors of above 10 Millions on a single chip. Ex: Embedded system, system on chip.
- Fabrication technology has advanced to the point that we can put a complete system on a single chip.
- Single chip computer can include a CPU, bus, I/O devices and memory.
- This reduces the manufacturing cost than the equivalent board level system with higher performance and lower power.