Download clampers - Book Spar

Problems
1)For the fig
sketch the
output
waveform.
What is the
maximum
positive
voltage? The
maximum
negative?
2)For the fig
sketch the
output
waveform. What
is the maximum
positive voltage?
The maximum
negative?
3) The diode
clamp shown in
the figure
protects the
sensitive circuit.
What are the
limiting levels?
4)For the fig what
is the maximum
positive output
voltage? Maximum
negative output
voltage? Sketch
output the
waveform .
If the circuit acts as
biased clamp for
sine wave input of
20mVwhat is the
protection level.
CLAMPERS
• Clamper is a network constructed of a diode, a
resister and a capacitor that shifts a waveform
to a different level without changing the
appearance of the applied signal.
• A clamper adds a dc voltage to the signal
• A positive clamper shifts its input waveform in
a positive direction, so that it lies above a dc
reference voltage.
• A negative clamper shifts its input waveform
in a negative direction, so that it lies below a
dc reference voltage.
Ideal Positive Clamper
Working
•On the first
negative half cycle
of the input the
diode is turned on.
•At negative peak
capacitor is fully
charged to Vp
Beyond negative peak
• Diode is off
• RLC is made much
larger than the time
period of the signal.
•Stiff Clamper
RLC > 100T
•Due to this reason
capacitor remains
fully Charged During
off time of diode
Clamping is not perfect since diode drops 0.7V.
Negative peak have reference level of -0.7V
Negative Clamper
Application
•Clampers are used in
•test equipment
• radar systems,
•electronic counter measure
systems
• sonar systems.
•These are commonly used in analog
television receivers to restore the DC
component of the video signal.
Peak To Peak Detector
Application
• In measuring nonsinusoidal signals such as
square, saw tooth etc .
Problems
1)For the fig
sketch the
output
waveform. What
is the maximum
positive voltage?
The maximum
negative?
2)For the fig
sketch the
output
waveform.
What is the
maximum
positive
voltage? The
maximum
negative?
3) Sketch the
output
waveform of the
clamper and
final output.
What is the dc
output voltage
with ideal
diode?
To a second
approximation?