What is a clipper circuit
Clipper circuit can clip off a portion of the input signal without disturbing the remaining part of the alternating waveform. Clipping circuit doesn’t need energy storage elements, the basic action of a clipper circuit is to remove certain portion of the waveform at certain levels as per the requirements. So a clipper circuit is a circuit that is used to clip off the unwanted portion of the waveform. Clipper circuit is also known as current limiters, voltage limiters, amplitude selectors and slicers. It is necessary for instrumentation controls and communications to frequently modify the shape of the waveforms, wave shaping is achieved by a simple combination of diodes, resistors and voltage sources such circuits are called clipper circuits. Clipper circuits can prevent a waveform from exceeding a certain limit, either positive or negative. This process is useful for signal shaping and circuit protection.
How does a clipper circuit work
Major components in a clipper circuit is a diode and a resistor and a DC battery are often used to fix the clipping level. By changing the battery voltage and by interchanging the position of various elements the input waveform can be clipped at different levels. An ideal diode will be used which will act as a closed switch when forward biased and act as an open switch when reverse biased.
What are the types of clipper circuit
Series and parallel clipper
Depending on the orientation of the diode the positive or negative region of the input signal is clipped off and there are two types of clippers. The series clipper circuit has the diode in series with the output and the parallel clipper circuit has the diode in a branch parallel to the output and there is no limit to the input wave shapes that can be applied to clipper circuit. By reversing the orientation of the diode in a series clipper circuit, the positive half cycle can be clipped from the input signal and this circuit is called a positive series clipper.
Positive clipper
Depending on the features of the diode the positive or negative region of the input signal is clipped off and accordingly the diode clippers may be a positive or negative clipper. The above figure shows a positive clipper. When the input signal is positive the diode is on and appears to be a short circuit at the output and the output voltage is zero. the diode is open when the input signal is negative and negative signal will appear across the output and the series resistor is kept much smaller than the load resistor by design. In a positive clipper, the positive half-cycle voltage of the input will be removed.
Negative clipper
The negative clipping circuit is almost the same as the positive clipping circuit it has only one difference. If the diode is reconnected with reversed polarity, the circuit will become for a negative series clipper and negative shunt clipper respectively.
Biased negative clipper
Biased clipper will be used when a small portion of positive or negative half cycles of the signal voltage is to be removed, when a small portion of the negative half cycle is to be removed then it is called as a biased negative clipper. In bias clipper when the input signal voltage is positive, the diode is reverse-biased and this will cause it to act as an open switch. Because of this, the total positive half cycle will appear across the load. If the input signal voltage is negative but does not exceed the battery voltage then the diode will remain reverse biased and most of the input voltage appears across the output. During the negative half of the input signal, the signal voltage will be more than the battery voltage then the diode is forward biased and conducts heavily.
What are the applications of clipper circuit
Clipper circuits are used in radars and digital computers. They are used when it is desired to remove the signal voltage above or below a specified voltage level. It is used in radio receivers for communication circuits where noise pulses that rise well above the signal amplitude are clipped down to the desired level.
What is a clamping circuit
A clamping circuit is a circuit that will reposition or clamp the input waveform to a defined DC level. The clamping circuit consists of a capacitor, diode and a resistor an independent DC biasing voltage can also be employed to provide an additional voltage shift. Clamping circuit is also known as DC restorers, clamper circuit can adjust the DC position of the waveform without knowing what the waveform actually is.
Positive clamper
In the positive half of the first cycle, the voltage across the capacitor cannot change instantaneously, so when the voltage on the input moves up, the voltage on the top of the diode has to follow this voltage. This reverse biases the diode which will cause it to act as an open, and thus the output voltage follows the input voltage. The diode will be forward biased as the input voltage drops into the negative half of the first cycle. The voltage across the capacitor cannot change continuously at the positive half of the first cycle. So if the voltage on the input moves up, then the voltage on the top of the diode has to follow this voltage.
Negative clamper
The diode conducts and acts as a short circuit during the positive half cycle then the capacitor will charge to the peak value of the input voltage and during this interval, the output which is taken across the short circuit will be zero, and during the negative half cycle, the diode is open. The negative clamper is almost the same as positive clamper, except the positive peak value of the waveform is clamped to ground, which will make the entire waveform negative. Components in a negative clamper circuit are the same as the positive clamper except the diode is reversed.