Operational amplifiers
Grounding the non-inverting (+) input produces an
inverting amplifier. The input and output signals are out of phase.
The common collector amplifier is used to
isolate the differential amplifier from the push-pull amplifier.
An op-amp is not normally constructed from individual components
it is packaged in an integrated circuit (IC).
The differential amplifier is the
key to the op-amp's versatility.
Grounding the inverting (-) input produces a
non-inverting amplifier. The input and output signals are in phase.
, common base amplifiers do not
not invert the input signal and have high voltage gains
Common Mode
operates in this mode when the inputs are in phase
Connecting several signals to the inverting (-) input produces a
summing amplifier. The output is the algebraic inverted sum of the inputs.
common collector amplifiers do not
invert the input signal and have a voltage gain of 1.
Op-amps use three circuits to performmany different functions.
1) The differential amplifier receives the inputs. 2)The common collector amplifier. Is used to isolate the differential amplifier from the push-pull amplifier. 3)push-pull amplifier.The output of the common collector amplifier is applied to the push-pull amplifier.
The differential amplifier can operate in one of two modes:
Difference Mode or Common Mode
Op-amp ICs are made from
P-type and N-type material, just like diodes and transistors.
Which circuit is used for power amplification in an op-amp?
Push-Pull Amplifier
INVERTING input.
The input with the negative (-) sign is the INVERTING input.
NON-INVERTING input.
The positive (+) labeled input is called the NON-INVERTING input.
The output signal is the difference
between the input signals. If the inputs are equal, the output is zero.
Using both inputs produces a
differential amplifier. The output is the difference between the inputs.
Depending on the inputs, Q1 is
either a common collector or common base amplifier.
Q2 is either a common base or common emitter amplifier, depending on
the inputs
The differential amplifier operates in this mode when
the inputs are 180° out of phase.
When the inverting input is grounded
the output is in phase with the input. Q1 is a common collector amplifier and Q2 is a common base amplifier.
When the non-inverting input is grounded,
the output is not in phase with the input. Q1 is a common base amplifier and Q2 is a common emitter amplifier.
The output of the push-pull amplifier is
the output of the op-amp.
Most of the amplification takes place in
the push-pull amplifier. Its power gain is high.
Differential amplifiers consist of
two transistors.
Operational amplifiers
use two inputs to determine the output.
The two inputs give op-amps
versatility.