Introduction

Part one of the Clipper Circuits introduced us to the two main types of clipper circuits: positive and negative clipper circuits. We delved deeply into the operation, applications, classifications, and circuit designs of positive clipper circuits. In Part 2, we will focus on negative clipper circuits, their operation, types, waveforms, and applications. Let’s explore the details in this article.

Negative Clipper Circuits

Negative clipper circuits are designed to attenuate the negative portions of the input signal. The diagram below represents a typical negative clipper circuit.

There are several types of negative clipper circuits, including:

• Negative series clipper
• Negative series clipper with a negative reference voltage, Vr
• Negative series clipper with a positive reference voltage, Vr
• Negative parallel clipper
• Negative parallel clipper with a negative reference voltage, Vr
• Negative parallel clipper with a positive reference voltage, Vr

Let’s dive deeper into these types of negative clipper circuits, their design, operation, and associated waveforms.

Negative Series Clippers

Figure 1: Negative Clipper Circuit

The Input Positive Cycle

When an input voltage is applied, the positive half-cycle of the input causes point A to become more positive relative to point B. This forward-biases the diode, causing it to act like a closed switch. As a result, the full input voltage appears across the circuit’s load resistor, R, producing an output voltage, Vo.

The Input Negative Cycle

During the negative half-cycle, point A becomes negative relative to point B. This reverse-biases the diode, causing it to behave like an open switch. The voltage across the load resistor becomes zero, resulting in an output voltage, Vo, of zero.

The Negative Series Clipper Waveforms

Figure 2: Negative Series Clipper Waveforms

By analyzing the waveforms, we can see that the negative portion of the waveform is clipped. This occurs because the voltage, Vo, passes across the load resistor, R. The slight deviation from the ideal waveform is caused by the diode’s conduction voltage, typically around 0.7V, which results in a small difference between the ideal and actual waveforms.

Negative Series Clipper with a Positive Reference Voltage, Vr

In this circuit, the diode is connected in series with the load resistor and biased using a positive reference voltage, Vr. The purpose of Vr is to attenuate the negative portion of the input waveform.

Below is the diagram for a negative series clipper with a positive reference voltage, Vr:

 

 

Figure 3: Negative Series Clipper with a Positive Reference Voltage, Vr Circuit Diagram

During the positive input cycle, the diode conducts when the voltage at the anode exceeds the voltage at the cathode. The cathode voltage remains equal to the reference voltage, and the resulting output waveform is shown below.

Negative Series Clipper with a Negative Reference Voltage, Vr

In this configuration, the diode is connected in series with the input signal, and the biasing is achieved using a negative reference voltage, Vr, to attenuate the negative portion of the waveform. The connection is shown in the figure below.

Figure 4: Negative Series Clipper with a Negative Reference Voltage, Vr Circuit Diagram

When a positive half-cycle is applied to the input, the diode becomes forward-biased, and the input voltage appears across the output. During the negative half-cycle, the diode becomes reverse-biased, preventing conduction. The result is that the output voltage is equal to the reference voltage, leading to clipping of the negative portion of the waveform immediately after the reference voltage is reached.

The waveform diagram is shown below:

Figure 5: Negative Series Clipper with a Negative Reference Voltage, Vr Waveforms

 

Negative Parallel Clipper

In a negative parallel clipper, the diode is connected in parallel with the input signal, and it clips the negative portion of the waveform. The circuit diagram for a negative parallel (shunt) clipper is shown below.

Figure 6: Negative Parallel Clipper Circuit Diagram

Input Positive Cycle

During the positive input cycle, point A becomes positive relative to point B. This reverse-biases the diode, causing it to behave like an open switch. The voltage across the load resistor equals the input voltage, and hence, Vi equals Vo.

Input Negative Cycle

For the negative cycle, point A becomes negative relative to point B, forward-biasing the diode and making it act like a closed switch. As a result, the voltage across the resistor becomes zero, as no current flows.

Waveforms

 

Figure 7: Negative Parallel Clipper Waveforms

From the waveforms, we can observe that only the negative peak of the waveform is clipped, caused by the voltage passing across the diode.

The Two-Way Clipper Circuit

This circuit combines both negative and positive clipper circuits. These are also known as combinational circuits.

The circuit and waveforms are shown in the figures below.

Figure 8: The Two-Way Clipper Circuit Diagram

The waveform for the two-way clipper is shown below:

Figure 9: The Two-Way Clipper Circuit Waveforms

Summary

This article has introduced negative clipper circuits and covered several types, as summarized below:

· Negative series clipper

· Negative series clipper with a negative reference voltage, Vr

· Negative series clipper with a positive reference voltage, Vr

· Negative