Diode Clipper Circuit - Biased, Unbiased, Positive and Negative

Diode Clipper Circuit - Biased Clippers, Unbiased Clippers, Positive Clippers, Negative Clippers, Shunt Clippers and Double Diode Clipper Circuits:

Clippers are also called amplitude selectors or slicers. A circuit arrangement is used to cut off the part of the signal.  Diode clippers can clip off unwanted parts of the waveform. We have set a reference point. The Signal port lies above or below the reference point clips off. You can think of a half-wave rectifier as the simplest form of clipper (see figure 1).

Figure 1 Simple clipper circuit or rectifier

The basic components of the clipping circuit are a diode and a resistor. In the above circuit, the negative half-cycle was eliminated. You can decide the clipping level of your own choice. To get the desired level of clipping, you have to add a DC source in series with the diode. These are called biased clippers.

Positive Clippers:

It removes the positive part of the input signal.

Negative Clippers:

It removes the negative part of the input signal.

Series Clippers:

In series clipper circuits, the diode is in series with input and output terminals.

Shunt Clippers:

In shunt clippers, the diode is in parallel with input and output terminals.

      

Example 1: Positive Series Biased Clippers:

Figure 2 Positive series clipper

1. Positive series clipper, diode D1 direction shows it is a positive clipper
2. Observe the circuit without sinusoidal input (V1).
3. D1 is reverse biased. Because of biasing voltage polarity. At anode 0V while at cathode +2V
4. Now consider a circuit with sinusoidal input  (V1)
5. During the positive half cycle more positive voltage at cathode +6V and +2V. The diode remains off. No voltage at the output

Vo = 0

6. During the negative half-cycle, the diode is forward biased for a small portion of the input wave. We have to evaluate the time of the diode.
7. A diode is forward biased when the anode is more positive than the cathode. The cathode is at 2V (biasing voltage). To make the diode forward bias, the applied voltage is less than -2V (for the ideal diode) or -2.7V (for the practical diode)
8. Apply KVL on the equivalent circuit (negative half cycle)

V1 - 2 - 0.7 +Vo = 0

Vo = - V1 + 2.7

Vo = -3.3V

Look at the output waveform (Blue). We get a new peak shifted in the upward direction. During the negative half, the cycle diode remains turned off until V1 reaches up to -2.7V.

It is simple, when the diode turns on, the signal appears at the output. And we have evaluated the on-time of the diode.

Example 2: Shunt Biased Negative Clippers :

Figure 3 Shunt clippers/negative clippers

1. The figure above is a negative shunt clipper. The direction of the diode shows it is a negative clipper
2. Have a look at the circuit diagram, output is taken across the diode and  DC voltage source
3. During the positive half cycle, the diode is reversed biased (open circuit). No voltage drop occurs. A positive half cycle appears at the output
4. During the negative half-cycle, voltage half-cycle, a small portion of the input wave appears at the output, rest of the portion clips
5. We get the output until the diode remains off. When does diode forward bias?
6. The diode turns on when the anode is at a higher potential than the cathode
7. The anode is at -3V. To make it forward bias input is less than -3.7V (consider diode drop)
8. Look at the output waveform (blue), it clips after -3.7V

It is simple, when the diode turns off, the input signal appears at the output.

Example 3: Biased Shunt Clippers Clippers | Double Diode Clippers:

Figure 4 Double diode clippers

I would like to explain the double diode clipper with biasing level 3V.

During the positive half cycle, D2 reverse bias D1 forward bias for a small portion of the input waveform.

1. D1 turns on when the anode is at a higher potential than the cathode.
2. Look at D1, the cathode is at +3V. To turn on (forward bias) the D1, applied voltage greater than 3.7V
3. After 3.7V, no voltage appears at the output
4. Look at the output voltage waveform (blue) which clips off after 3.7V

During the negative half-cycle, D1 reverse bias, and D2 forward bias for a small portion of the input waveform.

1. D2 turns on when the anode is at a higher potential than the cathode
2. Look at D2, the anode is at -3V. To turn on (forward bias) the D2, applied voltage less than -3.7V
3. After -3.7V, no voltage appears at the output
4. Look at the output voltage waveform (blue) which clips off after -3.7V

Applications of clipping circuit:

• It is used in wave shaping in such a way that it limits the peak of the input signal. It also removes the unwanted peaks
• It is used in communication systems, signal processing

In the end:

Dear students! You don't need to apply KVL or solve mesh equations. You just need to have some practice. Use any circuit analysis software. Draw different clipper circuit configurations

Analysis output waveforms. After some practice, you can easily draw the output waveforms.