11.12: Clamper Circuit
A clamper circuit, also known as a DC restorer, represents a specialized variant of the rectifier circuit, notable for its method of taking the output across the diode rather than the capacitor. This configuration lends to several distinctive applications, particularly in handling square wave inputs.
Within this circuit, the diode's orientation prompts the capacitor to charge up to the level of the most negative peak of the input signal. Upon reaching this state, the diode ceases to conduct, effectively locking the capacitor's voltage at a constant level. This mechanism results in the output voltage being the original input waveform, elevated by a value equal to the voltage across the capacitor (VC).
The primary function of the clamper circuit is to adjust the baseline of the waveform. By default, it raises the lowest point of the waveform. Altering the diode's polarity inverses this effect, clamping the waveform's highest peak at zero volts instead. This capability is particularly beneficial in applications involving pulse signal transmission through systems with capacitive coupling. Since capacitive coupling inherently eliminates the DC component of a signal, the clamper circuit plays a critical role in reinstating this DC level, facilitating accurate duty cycle modulation.
Including a load resistor across the diode introduces additional complexity to the circuit's operation. In such configurations, the capacitor discharges whenever the output rises above ground level, subtly altering the output voltage. The capacitor replenishes its charge in steady-state conditions, ensuring the circuit's effectiveness in restoring and maintaining the desired DC component within a signal.
