The Very Large Scale Integration (VLSI) technology today has made possible integration of millions of transistors on single Integrated Circuit (IC) chip. Modern VLSI has attained features in sub nanometer, e.g. .06-micron technology is very popular these days. The search is towards bringing more and more transistors in single chip by going more towards deep sub micron technology. Now the art is system – on – chip or integrating a whole system on a single IC chip that comprises of several analog and digital functions.
The VLSI design can be classified into three categories depending on the way of designing: Analog design, Digital design and Mixed Signal (both analog and digital) design. The regularity and granularity of digital circuits have made Digital designs automated to a good extent, with the help of CAD tools, given a behavioral description of the function desired. Whereas for analog circuit design a more hands on design approach is required.
CMOS Technology
Nowadays most popular Integrated Circuit Design Technology are: Bipolar and Metal Oxide Semiconductor (MOS). The classifications of various groups are described in Fig 1.1.
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| Categories of Silicon Technology |
Fig 1.1 : Categories of Silicon Technology
When design of system on chip is the question then CMOS technology gives more advantages compared to the others. So, analog design using CMOS is very popular today. Bipolar Complementary Metal Oxide Semiconductor (BiCMOS) technology is used often when a high degree of performance is required. BiCMOS is much costlier then CMOS design. Hence still the most prevalent design technique is CMOS.
