Posted by Tittu Thomas , 5/12/2012Clipping circuits
Here, i am going to explain the working and output waveforms of shunt(parallel) clipping circuits using diodes and resistors.
Clipping circuit is commonly used to clippoff, any part of an input waveform (either positive or negetive) at any levels.
Principle used in Shunt clippers using DIODES
The basic principle used in diode clippers is that, The diode conducts only in one direction (Forward biased) and it blocks current when reverse biased.
ie; When the input wave makes the diode forward biased , it will conducts the current and it will goes to ground but it will appears across the output.
By using diode clipper, we can be able to clip the wave at any levels, by furnishing an additional voltage source.
The fig. Shows the circuit diagram and output waveform of positive clipper.
In the fig. I am neglected the voltage drop across diode during forward bias, due to the cutin voltage of diode( which may vary according to the diodes we used ). If we are going to consider this drop which will appears on output during conduction hence on the waveform.
The fig. shows the circuit diagram and output waveform of negetive clipper. Similarly in positive clipper it will works on negetive side too.
Having only one difference that the diode is connected just opposite to that of positive clipper.
POSITIVE CLIPPER AT 3 VOLTS.
The fig. Shows the circuit diagram and waveform of the positive clipper at 3V. Till 3V the diode is in reverse bias so the output is present.
After that the input waveform exceeds 3v the diode get in forward biases and the wave clipped off. If we are considering the voltage drop of 0.6v the output may clipped at the level of 3+0.6 volts =3.6v
NEGETIVE CLIPPER AT 3 VOLTS.
The fig. Shows the circuit diagram and output waveform of negetive clipper at 3v. The working is similar to that of positive clipper at 3v.
Except that the diode and cell is just connected in opposite. So the negetive going wave at -3v is clipped
Some tricks to learn about CLIPPING CIRCUITS
¤ Look for the anode(positive) of diode in the circuit diagram, if it is in upperside, the top portion of the wave get clipped off.
¤ check whether the diode is connected in series with cell, if yes it will clipped at a level equal to the sum of voltage source and the diode drop.
¤ By using these tricks, you can easily draw the output waveform of any clipping circuits and viceversa.
Got Confused? Comment it here i will solve soon.