Page 172 - Concise Encyclopedia of Robotics

Integrated Circuit
Modern IC appliances employ modular construction. Individual ICs
perform defined functions within a circuit board; the circuit board or
card, in turn, fits into a socket and has a specific purpose. Computers,
programmed with customized software, are used by technicians to locate
the faulty card in a system. The card can be pulled and replaced, getting the
system back to the user in the shortest possible time.
Linear ICs
A linear integrated circuit is used to process analog signals such as voices,
music, and most radio transmissions. The term “linear” arises from the fact
that the instantaneous output is a linear function of the instantaneous input.
An operational amplifier (also called an op amp) consists of several
transistors, resistors, diodes, and capacitors, interconnected to produce
high gain over a wide range of frequencies.An op amp has two inputs and
one output.When a signal is applied to the noninverting input, the output
is in phase with it; when a signal is applied to the inverting input, the
output is 180° out of phase with it.An op amp has two power supply con-
nections, one for the emitters of the transistors (V ee) and one for the col-
lectors (V cc ). The symbol for an op amp is a triangle. The inputs,
output, and power supply connections are drawn as lines emerging from
the triangle. The gain characteristics of an op amp are determined by
external resistors. Normally, a resistor is connected between the output
and the inverting input. This is the closed-loop configuration. The feed-
back is negative, causing the gain to be less than it would be if there were
no feedback (open-loop configuration).
A closed-loop amplifier using an op amp is shown in Fig. 1. When a
resistor–capacitor (RC) combination is used in the feedback loop of an
op amp, the amplification factor varies with the frequency. It is possi-
ble to get a low-pass response, a high-pass response, a resonant peak,
or a resonant notch using an op amp and various RC feedback
arrangements.
A voltage-regulator IC acts to control the output voltage of a power
supply. This is important with precision electronic equipment. These
ICs are available in various different voltage and current ratings. Typical
voltage-regulator ICs have three terminals.They look like power transistors.
A timer IC is a form of oscillator. It produces a delayed output, with
the delay being variable to suit the needs of a particular device. The delay
is generated by counting the number of oscillator pulses. The length of
the delay is adjusted by means of external resistors and capacitors.
A multiplexer IC allows several different signals to be combined in a
single channel via time-division multiplexing, in a manner similar to that

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