Amplifiers 1st SEM Electronic And Communication

1. AMPLIFIER
BESCK104C
PRESENTED BY :
TEJAS (ERP: 1RR23F221)

2. AMPLIFIER
 An amplifier is an electronic device that can increase the
power of a signal.
Vout = Av . Vin
 The amount of amplification provided by an amplifier is
measured by its gain.
 Gain is the ratio of ouput to input.
Voltage Gain Av = Vout / Vin

4. TYPES OF AMPLIFIERS
 AC coupled amplifier
 DC coupled amplifier
 Large signal amplifier
 Small signal amplifier
 Audio frequency amplifier
 Wide band amplifier
 Radio frequency amplifier

5. AC COUPLED AMPLIFIER
 AC coupled amplifier is a conventionalamplifier that uses
capacitors or transformers to block DC voltage between stages.
This causes the entire amplifierto act as a high pass filter which
blocks very low frequencysignals. Frequencies down to 0 Hz
because there is no DC blocking between stages.
DC COUPLED AMPLIFIER
 A direct-coupled amplifier or DC amplifier is a type of amplifierin
which the output of one stage of the amplifier is coupled to the
input of the next stage in such a way as to permit signals with zero
frequency, also referred to as direct current, to pass from input to
output.

6. LARGE SIGNAL AMPLIFIER
 Large signal amplifiers also known as power amplifiers are capable of
providing large amount of power to the load. They are used as last stage
in electronic systems. A power amplifier takes the d.c. power supply
connected to the output circuit and converts it into a.c. signal power.
SMALL SIGNAL AMPLIFIER
 Those amplifiers which handle small input a.c. signals (a few µV or a few
mV) are called small-signal amplifiers. Voltage amplifiers generally fall
in this class. The small-signal amplifiers are designed to operate over
the linear portionof the output characteristics.

7. AUDIO FREQUENCY AMPLIFIER
 Audio frequency amplifiers operate in the band of frequencies
that is normally associated with audio signals. The audio
frequency is in between 20 Hz to 20 kHz.
WIDE BAND AMPLIFIER
 Widebandamplifiers are capable of amplifyinga very wide range
of frequencies, typically from a few tens of hertz to several
megahertz.
RADIO FREQUENCY AMPLIFIER
 Radio frequency amplifiers operate in the band of frequencies
that is normally associated with radio signals. The radio
frequency is from 100kHz to over 1GHz.