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Electronic amplifiers can be classified in many different ways.
Some common classifications for amplifiers are presented below.
Classification by Signal Type
Amplifiers may be classified based on the type of signal that they
amplify. Thus, an amplifier that amplifies voltage signals is
a voltage amplifier, while a buffer amplifier is one that amplifies
current signals. An amplifier that amplifies both the voltage
and current is classified as a power amplifier.
Classification by Common
Terminal Connection
Amplifiers consist of active devices (such as
bipolar and field-effect transistors) that can be connected such
that there is a common terminal between the input and the output.
One common way of classifying amplifiers is in terms of their common
terminal connection. For instance, a common-emitter amplifier means
that the active device is a bipolar transistor whose emitter
terminal is common to the input and the output side.
Classification by
Frequency Range
Amplifiers
may also be
classified according to the frequency range of the signals they can
amplify. Categories under such a classification include: 1) DC
amplifiers; 2) Audio Frequency (AF) amplifiers – 20 Hz to 20 kHz; 3) Video
amplifiers – several MHz; and 4)
Ultra High Frequency (UHF) amplifiers – up to a few GHz.
Classification by Function
Amplifiers
may be classified according to their basic function or output
characteristics. Some of these functional classifications are as
follows:
- servo amp
:
an amp
with an integrated
feedback loop to actively control the output at the desired
level
- linear amp
:
an amp
with a precise amplification factor over a wide range of
frequencies, often used to boost signals for relay in communications
systems
-
non-linear amp
:
an amp
that amplifies only a specific narrow or tuned frequency, to the
exclusion of all other frequencies
- RF amp :
an amp designed for use in the radio frequency
range of the electromagnetic spectrum, often used to increase the
sensitivity of a receiver or the output power of a transmitter
- audio amp :
an amp designed for use in reproducing audio frequencies, with special considerations made for
driving speakers
-
operational amp :
a low power amp that can perform mathematical operations
Classification by Interstage Coupling Method
Audio amplifiers are sometimes classified by the method
used in the coupling of the signal at the input, output, or between
stages. Different types of coupling methods include:
the R-C coupled amplifier; the L-C coupled amplifier; the transformer-coupled amplifier; and the direct-coupled amplifier.
Classification by
Type of Load
Another way of classifying amplifiers is by the
type of load that they drive: 1) untuned amps - amplify
audio and video with no tuning required; 2) tuned amps (RF amps) -
amplify a single radio frequency
or band of frequencies
Classification by
Angle Flow or Conduction Angle
A letter
system for classifying amplifiers also exists, wherein amplifiers
fall under class A, class B, class C, and so on. This classification
system is based on the amount of time that the amplifier's active
components are conducting electricity, with the duration measured in
terms of the number of degrees of the sine wave test signal.
See also: amplifier classes.
See Also:
What is an Amplifier;
Amplifier Classes;
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