Clipping Circuit | Electrical4U

Contents

💡

Key learnings:

Clipping Circuit Definition: A clipping circuit is a wave shaping circuit that alters the output waveform by removing parts of the input signal without distorting the remaining waveform.
Types of Clippers: There are various types of clipping circuits, including diode clippers, transistor clippers, unbiased clippers, and biased clippers.
Positive and Negative Clippers: Positive clippers remove the positive half cycles of the input voltage, while negative clippers remove the negative half cycles.
Biased Clippers: Biased clippers remove small portions of the positive or negative half cycles of the input signal using a DC bias voltage.
Applications: Clipping circuits are used in TV transmitters and receivers, noise limiters, circuit protection, and wave generation.

A clipping circuit is a wave-shaping circuit that removes parts of the input so the remaining output keeps its shape.
The clipping circuit has no energy storage elements (capacitors). It uses linear (Resistors) and nonlinear parts (transistors or junction diodes). It selects the part of a waveform that sits below or above a chosen reference voltage. The same circuit is also called a slicer, clipper, limiter or amplitude selector.

Classification of Clipping Circuit

According to non linear devices used –
1. Diode Clippers.
2. Transistor Clippers.
According to biasing –
1. Unbiased Clippers.
2. Biased Clippers.
According to configuration used –
1. Series diode clippers.
2. Shunt or Parallel diode clippers.
3. A series combination of reference supply, resistor and diode.
4. Multi-diode clippers comprises of a number of diodes, resistors and reference voltage.
5. Two emitter-coupled transistors functioning as an over driven difference amplifier.
According to level of clipping –
1. Positive clippers.
2. Biased clippers.
3. Negative clippers.
4. Combination clippers.

Diode Clippers

A clipper needs at least two parts: an ideal diode and a resistor. A DC battery can set the clipping level (Figure 1). When the diode is forward biased it acts as a closed switch. When it is reverse biased it acts as an open switch. Changing the battery voltage or swapping the parts changes which part of the input is clipped.

Positive and Negative Clippers

Positive clippers:
Positive clippers remove the positive half cycles of the input voltage. In a positive series clipper, the diode is reverse biased (output is zero) when the input is positive and forward biased when the input is negative.

In positive shunt clipper, when the input is negative, the whole input voltage appears across the resistor RL or diode (if R<<r_{L). When R<<r_{L, this circuit will operates as voltage divider and its output voltage is (figure 3).

When the diode is connected in reverse polarity in the circuits of positive series clipper and positive shunt clipper, it becomes negative series clipper and negative shunt clipper respectively (figures 4 and 5). These clippers can eliminate the entire negative half cycle of input voltage.

The clippers discussed above are considered as the circuits with ideal diode. But if the barrier potential (V₀) is considered (Si = 0.7 V and Ge = 0.3 V), the output voltage of positive and negative clippers are shown below.
</r_</r}}

Biased Clippers

In some cases, we need to eliminate a tiny portion of positive or negative half cycles of the input signal voltage. In that case we use biased clippers.
While during the negative half cycle of input signal in biased negative clipper circuit, it removes the input signal voltage when it is greater than the battery voltage. When the battery and diode is reversed, the clipping can be changed to biased positive clipper (Figure 7).