c. The Hybrid IC.
The monolithic and thin film processes are sometimes
combined to make a hybrid IC.
The resulting hybrid can have the high-quality
diodes and transistors formed in the monolithic IC and the high-quality resistors
and capacitors formed in the thin film process.
Hybrid IC's are also made by
mounting individual chips, connected by fine wires, in the same package.
This
method, called the chip and wire method, is shown in figure 3-10. It allows more
complicated circuitry and improves isolation between components.
Figure 3-10.
A chip and wire hybrid IC.
d. Applications.
Originally conceived for military equipment, IC's are now
also being used in commercial products ranging from automobiles to hearing aids.
Basically, IC's are divided into two categories--linear and digital.
(1) Linear. Linear, or analog, IC's produce outputs directly proportional
to their inputs. They are used for transmitter and receiver circuits,
such as amplifiers (audio, video, AF, and IF), squelch switches,
mixers, oscillators, and other linear circuit functions.
Most linear
IC's must be custom-made because the requirements of each circuit are
usually different.
Figure 3-11 shows a partial schematic of a radio
receiver that uses linear IC's. The IC's are represented by triangles,
and the lines extending from them represent the leads to the IC
package. In the blown-up portion of the figure, you see the detailed
schematic of the IF amplifier.
Although the IF amplifier contains 13
different components, it requires no more space than a conventional
Because of this and the fact that IC's need so little
power to operate, some of the larger communication systems of today
will be reduced to manpack size in the future.
(2) Digital.
Digital IC's perform switching functions in logic circuits.
Because digital IC's operate with low power, are used thousands of
times in the same form, and can operate effectively despite loose
tolerances, they have proved ideal for integration.
Digital IC's
include logic gates, flip-flops, counters, and shift registers.
The
entire circuit is contained in a single monolithic chip, and is used in
high-speed computers.
One big advantage of digital IC's over
conventional digital circuits is that they operate faster.
Some
digital IC's can operate in 400 trillionths of a second.
309 L3
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