Precision Rectifier. I NTRODUCTION The precision rectifier is also known as a super diode. It is a...
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Transcript of Precision Rectifier. I NTRODUCTION The precision rectifier is also known as a super diode. It is a...
Precision Rectifier
INTRODUCTION
The precision rectifier is also known as
a super diode.
It is a configuration obtained with an operational
amplifier in order to have a circuit behaving like
an ideal diode and rectifier.
It can be useful for high-precision signal
processing.
PRECISION RECTIFIER
BASIC CIRCUIT
The basic circuit implementing such a
feature is shown on the right, where RL can
be any load.
BASIC CIRCUIT OF PRECISION RECTIFIER
CONT.,
When the input voltage is negative, there
is a negative voltage on the diode, too, so it
works like an open circuit, there is no
current in the load and the output
voltage is zero.
CONT.,
When the input is positive, it is amplified by the
operational amplifier and it turns the diode on.
There is current in the load and, because of the
feedback, the output voltage is equal to the
input.
CIRCUIT DIAGRAM
CONT.,
In fact the threshold of the super diode is
not actually zero, as it should be for an
ideal one, but it equals the threshold of the
normal diode divided by the gain of the
operational amplifier, that is almost zero.
SATURATION
When the input becomes negative, the
output of the operational amplifier can
easily become greater than the voltage
supplied to the op-amp, thus causing
saturation.
CONT.,
If the input becomes positive again, the
op-amp has to get out of the saturation to
amplify again.
This change takes some time, and this
greatly reduces the frequency response
of the circuit.
IMPROVED PRECISION RECTIFIER CIRCUIT
PRECISION HALF WAVE RECTIFIER
PRECISION FULL WAVE RECTIFIER
PEAK DETECTOR
With little modifications basic precision rectifier
can be used also for detecting peak levels of
signal.
In the following circuit a capacitor keeps the
peak voltage level of signal and switch can be
used for resetting detected level.
PEAK DETECTOR
THE END
……. Thank You …….