A clipper is an electronic circuit that removes or “clips” portions of an input waveform that exceed a specified voltage level without distorting the remaining signal. It is used in signal processing and circuit protection applications. Discover the basics of clippers in electronics, their types, working principles, applications, advantages, and disadvantages. Learn how clippers shape waveforms and protect circuits from voltage spikes.
Clippers circuits are an important part of electronics. They are used to limit the voltage level of a signal. Clippers in electronics are simple circuits that remove a portion of the input waveform. These circuits are widely used in communication systems, signal processing, and voltage regulation. By regulating voltage levels, these circuits safeguard sensitive electronic components from potential damage caused by voltage fluctuations.
Clippers can be designed using diodes, resistors, and biasing elements to achieve the desired waveform shaping. They play a crucial role in modifying waveforms without affecting the overall signal frequency. Their precise signal-clipping capability makes them valuable in various electronic applications, enhancing circuit safety and operational efficiency.
What is Clipper?
A clipper circuit is an electronic circuit that removes or “clips” a part of the input signal. It restricts the voltage to a certain level, preventing it from exceeding a predefined limit. Clippers electronics circuits are commonly used in signal processing to shape waveforms by eliminating unwanted portions. These circuits ensure that signals remain within a specified range, protecting electronic components from excessive voltage. Clippers also help in reducing noise and improving signal integrity in communication systems and power electronics.
Types of Clippers
The connection and orientation of the diode with the input voltage and the load are used to categorize the different types of clippers. Clippers are classified into three main types: Series Clippers, Parallel Clippers, and Dual Clippers.
Series Clippers
Series Clippers have the diode connected in series with the load. These clippers can be further divided into positive and negative clippers based on the polarity of the clipped portion.
Series Positive Clipper
A series positive clipper removes the positive part of the input signal. It allows only the negative part to pass through.
Vi is applied as the input signal, and the load resistor receives the output. The voltage at point A is higher than point B during the input’s positive half-cycle. As a result, there is no current conduction, and the diode is in reverse bias. There is no voltage drop at RL because the input signal cannot pass. As a result, the output does not display the positive half cycle, as shown in the figure.
During the negative half-cycle of the input signal, the voltage at point A is lower than that at point B, causing the diode to become forward-biased and allowing the signal to pass through it. The signal is visible throughout RL, and the negative half-cycle appears at the output after passing through the circuit. This type of clipper is useful in applications where only the negative part of the waveform is required. It is widely used in waveform shaping, voltage limiters, and circuit protection applications.
The series positive clipper ensures that any voltage exceeding a certain level is removed, making it beneficial in preventing damage to electronic components. It can be implemented using a simple diode and a resistor, making it cost-effective and easy to use in various electronic designs. It shows how it clips the positive half of the input waveform and allows the negative half, as shown in the above figure.
Series Positive Clippers with Bias
In a clipper circuit with biasing, only a part of the half-cycle is clipped, not the entire half. A series of positive clippers with either positive or negative biasing is used to achieve the desired waveform.
Positive Bias
In a positive clipper circuit, the positive terminal of the battery is connected to the P side of the diode, as shown below.
During the positive half cycle, the diode turns off because the voltage at point A is higher than at point B. However, another voltage source is connected, with its positive terminal linked to the P side of the diode. This voltage source provides a forward bias to the diode.
If the input voltage is lower than the battery voltage, the diode remains forward-biased and conducts. This allows the signal to appear at the output. When the input voltage exceeds the battery voltage, the diode becomes reverse-biased and stops conducting. In this case, the output voltage remains equal to the battery voltage Vb.
During the negative half cycle, the input and battery voltage keep the diode in forward bias. As a result, the input signal passes through, producing the output signal.
Negative Bias
In a series positive clipper circuit with negative bias, the battery is connected in reverse with the diode, as shown in the diagram below.
- During the positive half cycle:
- The input voltage and the negative battery voltage cause the diode to remain reverse-biased.
- Since the diode does not conduct, the output voltage remains equal to the negative battery voltage.
- During the negative half cycle:
- The input voltage reverses polarity, which would typically forward-bias the diode.
- However, the negative battery voltage reverses the diode’s bias, preventing conduction.
- If the input voltage exceeds the battery voltage, the diode becomes forward-biased, allowing the input signal to appear at the output.
- Otherwise, the output remains at the battery’s negative voltage.
Series Negative Clipper
A series negative clipper circuit is designed to remove the negative half of the input signal. Its circuit diagram is shown below.
During the positive half cycle of the input voltage, the diode becomes forward-biased. This allows the input signal to pass through the diode, resulting in the same waveform appearing at the output.
In the negative half cycle, the diode becomes reverse-biased and stops conducting. Since no current flows through the circuit, the negative portion of the input signal is clipped, and the output remains at zero voltage. This type of clipper is useful in applications where only the positive half of the waveform is needed.
Series Negative Clippers with Bias
Instead of completely removing the negative half of the waveform, a series negative clipper circuit can be modified by adding a positive or negative bias voltage using a battery. This biasing allows control over how much of the negative half-cycle is clipped. By adjusting the battery voltage, a portion of the negative cycle can be retained while the rest is clipped, shaping the output waveform as needed.
Positive Bias
During the positive half cycle of the input signal, the diode is naturally forward-biased. However, the presence of a battery introduces an opposing bias. This means that the diode’s conduction is influenced by both the input voltage and the battery voltage.
As a result, the diode will only conduct when the input voltage exceeds the battery voltage. If the input voltage is lower than the battery voltage, the diode remains reverse-biased, preventing conduction. This setup allows controlled clipping, ensuring that only a specific portion of the waveform is modified.
Initially, when the input voltage is lower than the battery voltage, the diode remains reverse-biased and does not conduct. As a result, the output stays at the battery voltage.
As the input signal increases and surpasses the battery voltage, the diode becomes forward-biased, allowing the input signal to pass through. This means the output follows the input signal only when it exceeds the battery voltage, as shown in the figure.
During the negative half cycle, both the battery voltage and the input voltage keep the diode reverse-biased. Since the diode does not conduct, the output remains at the battery voltage throughout the entire negative half cycle.
Negative Bias
During the positive half cycle of the input signal, the battery voltage helps to keep the diode forward-biased. As a result, the input signal passes through the diode without clipping. This means that the output waveform during the positive half cycle remains unchanged and is the same as the input signal.
During the negative half cycle of the input signal, the input voltage tries to push the diode into reverse bias. However, the battery voltage applies a forward bias to the diode. The diode will conduct only when the battery voltage is higher than the input voltage.
At the beginning of the negative half cycle, if the input voltage is lower than the battery voltage, the diode remains forward-biased, allowing the signal to pass through. As the input voltage increases beyond the battery voltage, the diode becomes reverse-biased and stops conducting. At this point, the output displays only the battery voltage, as shown in the above figure.
Parallel Clipper
Parallel Clippers have the diode connected in parallel with the load. Like series clippers, they are also classified as positive and negative clippers.
Parallel Positive Clipper
The shunt positive clipper removes the positive half of the input waveform. The circuit diagram of the shunt positive clipper is shown below.
During the positive half cycle, the voltage at point A is higher than at point B, making the diode forward-biased. This causes the diode to conduct, resulting in no voltage difference at the output.
When the input signal enters the negative half-cycle, the voltage polarity at points A and B reverses, turning the diode reverse-biased. As a result, the diode blocks the input signal, and the voltage across it appears as the clipper’s output.
Thus, the shunt positive clipper effectively removes the positive half of the input signal while allowing the negative half to pass through.
Parallel positive clipper with Bias
A fixed voltage source, such as a battery, is introduced during the biasing process to modify the waveform further. The voltage source can be connected using either positive or negative biasing, depending on the desired clipping effect.
Positive Bias
During the positive half cycle, the input voltage forward-biases the diode. However, the battery voltage applies an opposing bias. The diode’s conduction depends on the combined effect of both voltages. If the input voltage exceeds the battery voltage, the diode becomes forward-biased and conducts. Otherwise, it remains reverse-biased and blocks the signal.
When the input signal is lower than the battery voltage, the diode remains reverse-biased, allowing the output signal to appear. However, once the input voltage exceeds the battery voltage, the diode starts conducting, and only the battery voltage is visible at the output.
During the negative half cycle, the input voltage and battery voltage keep the diode reverse-biased. Consequently, the entire negative half-cycle of the input signal appears at the output.
Negative Bias
During the positive half cycle, the input signal and battery voltage forward-bias the diode. As a result, the diode conducts for the entire cycle, and the output remains at the battery voltage.
During the negative half cycle, the diode experiences opposing influences from the battery voltage and input signal. The battery voltage forward-biases the diode, while the input signal reverse-biases it. The overall state of the diode is determined by the combined effect of both voltages.
Initially, when the input voltage is lower than the battery voltage, the diode remains forward-biased, and the output displays the battery voltage. However, as the input voltage surpasses the battery voltage, the diode becomes reverse-biased. This change allows the input signal to appear at the output, effectively altering the waveform based on the voltage levels.
Parallel Negative Clipper
Negative parallel clippers remove the negative half of the input waveform, allowing only the positive half to pass through.
During the positive half cycle, the diode remains reverse-biased, preventing the signal from passing through, resulting in the positive half appearing at the output. In contrast, during the negative half cycle, the diode becomes forward-biased and conducts the signal, leaving no voltage at the output. Thus, the shunt negative clipper effectively removes the negative half of the input waveform.
Parallel Negative Clipper with Bias
Positive or negative biasing is applied to the shunt negative clipper to modify its waveform further. This is achieved by connecting a battery with either positive or negative biasing. Adjusting the battery’s voltage allows for precise control over the waveform alteration.
Positive Bias
During the positive half cycle, the diode is forward-biased by the battery voltage but reverse-biased by the input voltage. As a result, the diode remains conducting unless the input voltage exceeds the battery voltage. When this happens, the diode becomes reverse-biased, allowing the input signal to appear at the output.
When the input signal is initially lower than the battery voltage, the diode remains forward-biased and conducts, causing the output to display only the battery voltage. However, when the input signal surpasses the battery voltage, the diode becomes reverse-biased, allowing the input signal to appear at the output, as shown in the figure.
During the negative half cycle, the diode remains forward-biased due to both the input signal and the battery voltage. As a result, it continues to conduct, and the output consistently displays the battery voltage throughout the entire negative cycle.
Negative Bias
During the positive half cycle, the diode is reverse-biased due to both the input voltage and the battery voltage. As a result, the diode blocks the signal, preventing it from passing through. Consequently, the output retains the signal throughout the entire positive half cycle.
During the negative half cycle, when the input voltage is higher than the battery voltage, the diode conducts, allowing the signal to pass. However, when the input voltage drops below the battery voltage, the diode becomes reverse-biased, blocking the input signal. As a result, only the battery voltage appears at the output when the input voltage is lower. Once the input voltage exceeds the battery voltage, the diode starts conducting again, influencing the output accordingly.
Dual Clipper Circuit
In a double clipper, also known as a combination clipper, two diodes and a load resistor are connected in parallel. This circuit is designed to remove specific portions of the positive and negative halves of the input signal. It is commonly used when both peaks of the waveform need to be clipped, ensuring that only the desired voltage range is allowed to pass through while eliminating unwanted signal variations.
The operation of a double clipper circuit is based on a simple principle. If both diodes are reverse-biased or non-conducting, the input signal appears across the diodes and at the output. However, when either diode starts conducting, the corresponding battery voltage is displayed at the output.
During the positive half cycle, diode D1 is forward-biased by the input voltage, while diode D2 remains reverse-biased. However, considering the battery voltages (VB1 and VB2), both diodes are reverse biased. Initially, since the input voltage is lower than VB1, diode D1 remains reverse-biased, and the input signal appears at the output. Once the input voltage exceeds VB1, D1 starts conducting, and VB1 is displayed at the output.
In the negative half cycle, the input voltage reverse biases D1 due to the combined effect of input voltage and VB1. Meanwhile, D2 is forward-biased by the input voltage but reverse-biased by VB2. Initially, when the input voltage is below VB2, D2 remains reverse-biased, and the output follows the input signal. Once the input voltage exceeds VB2, D2 conducts, and VB2 appears at the output.
Applications of Clipper Circuits
- Overvoltage Protection – Clipper circuits are used in power supplies to limit voltage and protect sensitive components from damage due to voltage surges.
- Signal Synchronization – Clippers are commonly used to extract synchronizing signals from composite video signals in television broadcasting.
- Noise Reduction – They help eliminate unwanted noise from an AC signal by clipping excessive amplitude variations.
- Waveform Shaping – Clippers modify waveforms to generate square, triangular, or other customized signals for various applications.
- TV Transmitters and Receivers – They are used in television circuits to process and shape signals effectively.
- Communication Systems – Clippers are employed in AM radio transmitters and receivers to control signal distortion and maintain signal integrity.
- Digital Circuit Design – They assist in converting analog signals into digital pulses by clipping excess voltage levels.
Advantages of Clippers
- Removes Unwanted Signal Portions – Clippers eliminate unnecessary parts of a signal, ensuring only the desired portion is processed.
- Reduces Noise – They help in filtering out noise by clipping unwanted amplitude variations in a signal.
- Protects Devices from Voltage Spikes – Clippers safeguard sensitive electronic components by limiting high voltage surges.
- Waveform Shaping – They modify signal waveforms to meet specific design requirements, such as converting sine waves into square or triangular waves.
- Minimizes Power Consumption – By limiting excessive voltage, clippers help in reducing power loss and improving circuit efficiency.
Disadvantages of Clippers
- Effect of Diode Capacitance – At high frequencies, the inherent capacitance of the diode can impact the clipper’s performance, leading to signal distortion.
- Signal Distortion – If the voltage across the diode drops suddenly, it can cause unwanted distortion in the clipped signal.
- Limited Signal Control – Clippers only limit the voltage but do not amplify or restore the signal, which may not be suitable for all applications.
Conclusion
Clippers play a crucial role in electronic circuits by limiting voltage levels and protecting devices from high voltage surges. The clipper circuit removes portions of a signal that exceed a predefined voltage while preserving the rest of the waveform. This makes them essential in applications requiring signal integrity and device protection. Clippers are broadly classified into series and parallel types, each serving specific purposes in signal processing. Their ability to modify waveforms makes them valuable in various electronic and communication systems.
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