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After the printed circuit boards were perfected, efforts to miniaturize electronic equipment were then
shifted to assembly techniques, which led to MODULAR CIRCUITRY. In this technique, printed circuit
boards are stacked and connected together to form a module. This increases the packaging density of
circuit components and results in a considerable reduction in the size of electronic equipment. Since the
module can be designed to perform any electronic function, it is also a very versatile unit.
However, the drawback to this approach was that the modules required a considerable number of
connections that took up too much space and increased costs. In addition, tests showed the reliability was
adversely affected by the increase in the number of connections.
A new technique was required to improve reliability and further increase packaging density. The
solution was INTEGRATED CIRCUITS.
An integrated circuit is a device that integrates (combines) both active components (transistors,
diodes, etc.) and passive components (resistors, capacitors, etc.) of a complete electronic circuit in a
single chip (a tiny slice or wafer of semiconductor crystal or insulator).
Integrated circuits (ICs) have almost eliminated the use of individual electronic components
(resistors, capacitors, transistors, etc.) as the building blocks of electronic circuits. Instead, tiny CHIPS
have been developed whose functions are not that of a single part, but of dozens of transistors, resistors,
capacitors, and other electronic elements, all interconnected to perform the task of a complex circuit.
Often these comprise a number of complete conventional circuit stages, such as a multistage amplifier (in
one extremely small component). These chips are frequently mounted on a printed circuit board, as shown
in figure 2-21, which plugs into an electronic unit.
Figure 2-21.—ICs on a printed circuit board.
Integrated circuits have several advantages over conventional wired circuits of discrete components.
These advantages include (1) a drastic reduction in size and weight, (2) a large increase in reliability, (3)
lower cost, and (4) possible improvement in circuit performance. However, integrated circuits are
