Clippers and Clampers are two types of circuits used in electronics to alter the shape of an input signal. They are commonly used in applications such as audio processing, video processing, and telecommunications. Understanding the difference between these two types of circuits and how they work is essential for any electronics enthusiast.
Clippers are circuits that remove or clip portions of an input signal. This is done to limit the amplitude of a signal and to prevent it from exceeding a specified maximum value. This can be useful in a number of applications where an input signal may contain unwanted spikes or high-frequency noise. There are two main types of clippers, diode clippers and transistor clippers.
Diode clippers are the simplest type of clipper. They use a diode in conjunction with a resistor and a capacitor to limit the amplitude of the input signal. When the input signal exceeds the forward bias voltage of the diode, it becomes a non-conductive material, effectively stopping the flow of current. This results in the removal of the portion of the input signal that exceeds the forward bias voltage.
Transistor clippers, on the other hand, use a transistor to clip the input signal. These clippers are more versatile than diode clippers, as they can be designed to clip signals at different levels and to have different clipping slopes. This makes them a popular choice for audio processing applications where a flat or steep clipping characteristic may be required.
Clampers, on the other hand, are circuits that alter the DC level of an input signal. They are used to add or remove a DC offset from a signal, effectively shifting the signal up or down on the voltage axis. This is useful in a number of applications where a signal needs to be centered around a specific DC level for further processing or for display.
There are two main types of clampers, diode clampers and op-amp clampers. Diode clampers are the simplest type of clamper. They use a diode in conjunction with a capacitor to add or remove a DC offset from the input signal. The DC offset is added to or removed from the signal by charging or discharging the capacitor through the diode.
Op-amp clampers, on the other hand, use an operational amplifier (op-amp) to add or remove a DC offset from the input signal. These clampers are more versatile than diode clampers, as they can be designed to add or remove any desired DC offset. They also have the advantage of being able to handle higher frequency signals compared to diode clampers.
Diode Clippers Circuit examples
Types of diode clippers
- Shunt Clippers
- Positive Shunt Clipper
- Negative Shunt Clipper
- Series Clippers
- Positive Series Clipper
- Negative Series Clipper
Shunt Clippers
In shunt clippers with diodes, the diode is placed in parallel to the output.
1. Positive Shunt Clipper
Positive shunt clipper are those which removes partly the positive signal amplitude during the positive signal excursion.
Shown below is circuit diagram and waveform output.
In the circuit above, a sine wave of 5V peak to peak is applied to the shunt positive clipper diode 1N4148 and the resistor is 4.7KOhm. From the waveform graph, we can see that the output does not contain all the positive part of the input signal, that is, part of the input waveform is clipped. The magnitude of the clipping is 0.7V, which is the forward voltage of the diode. The output signal has amplitude upto this forward voltage. The negative part of the input signal is passed through without clipping.
1.1 Positive Shunt Clipper with positive DC reference
If one wants to decrease the clipping so that more of the input positive signal appears at the output then we can add a DC reference voltage in series with the shunt diode as shown below.
Here a positive reference VREF of 1.5V is added in series with the shunt diode. The result is that the output signal has now increased magnitude of 0.7V+1.5V=2.2V. This is shown below.
1.2 Positive Shunt Clipper with negative DC reference
Similarly if we want to clip the input signal more negative such that the output signal has less of the input half cycle we can add a negative DC reference as shown below.
The input and output signal waveform for this type of clipper is shown below.
In this case, the output signal has magnitude of 0.7V-1.5V=-0.8V. The negative part is again fully passed without clipping.
2. Negative Shunt Clipper
In negative shunt clipper the diode is placed such that it is still parallel to the output but its cathode is now connected to ground as shown below.
The input signal is clipped in the negative cycle such that the output has negative voltage amplitude of -0.7V as shown below.
2.1 Negative Shunt Clipper with DC positive reference
By adding a DC positive reference in series with the negative shunt the input signal is clipped such that the output signal has amplitude of -0.7V+1.5V=0.8V
2.2 Negative Shunt Clipper with negative reference
The input and output waveform is shown below.
Here the input signal is clipped from negative side and the positive side is unaffected. The voltage at the negative side of the output signal is -0.7V-1.5V=-2.2V.
Series Clippers
1. Series negative clipper
The series negative clipper will remove the negative going part of the input signal and the output signal will only have positive going signal part of the input signal. The circuit diagram of a series negative clipper is shown below.
The waveform for this circuit is shown below.
1.1 Series negative clipper with DC positive reference
The Series negative clipper with positive reference circuit diagram is shown below.
And its input and output waveform is shown in the following graph.
1.2 Series negative clipper with DC negative reference
The Series negative clipper with negative reference circuit diagram is shown below.
In this case, the output signal has lower magnitude of -1.5V and upper magnitude of 4.3V.
2. Series positive clipper
The circuit diagram of a series positive clipper is shown below.
The waveform of input and output signal is shown below.
In this case, the output signal has lower magnitude of -4.3V.
2.1 Series positive clipper with DC positive reference
The circuit diagram of a series positive clipper with DC positive reference is shown below.
In this case, the output signal has lower magnitude of -4.3V and upper magnitude of 1.5V.
2.2 Series positive clipper with DC negative reference
The circuit diagram of a series positive clipper with DC positive reference is shown below.
In this case, the output signal has lower magnitude of -4.3V and upper magnitude of -1.5V.
Bidirectional Clipper circuit
By using two back to back diode clipper circuit with positive and negative reference voltage connected to the diodes we can clip both the negative and positive part of the input signal. Such a bidirectional diode clipper circuit is shown below.
The waveform below shows the output signal waveform illustrating the input signal waveform is clipped from above and below.
Note that the two reference voltages can be of different magnitude.
Diode Clipper circuit with Zener diode
Instead of the reference voltage we can use Zener diode which is often used in electronics circuits. Consider the following circuit where we have place a 2.4V zener diode.
During the positive half cycle of the input signal, when the input goes to +5V then both the clipping diode and the zener diode conducts and we have an output voltage of 0.7V+2.4V=3.1V. During the negative cycle of the input signal when the input goes to -5V, the clipping diode is turned off and we have an output voltage of -5V. This is shown in the graph below.
Zener Diode Clipper Circuit
Clampers
Clampers are circuits that clamps signal to a different DC level. In other words clamper circuit shifts the input signal level to a different dc level without changing the characteristics of the input signal.
Shown below are two basic clamper circuit implemented using diode. In both circuit implementation, the time constant RC must be much greater than the input signal time period T. That is, RC >> T so that there is adequate charging and discharging of the capacitor.
In conclusion, clippers and clampers are two types of circuits used in electronics to alter the shape of an input signal. Understanding the difference between these two types of circuits and how they work is essential for any electronics enthusiast. Both types of circuits have their own advantages and disadvantages, and the choice of which to use will depend on the specific requirements of the application.
