1. Waveform clipper
Two Zener diodes facing each other in series will act to clip both halves of an input signal.Waveform clippers can be used to not only reshape a signal, but also to prevent voltage spikes from affecting circuits that are connected to the power supply.
2. Voltage shifter
A Zener diode can be applied to a circuit with a resistor to act as a voltage shifter. This circuit lowers the output voltage by a quantity that is equal to the Zener diode’s breakdown voltage.
3. Voltage regulator
A Zener diode can be applied in a voltage regulator circuit to regulate the voltage applied to a load, such as in a linear regulator.
Zener Diode as Voltage Regulator
The term regulator means which regulates or controls. Zener diode can work as a voltage regulator if it is introduced in a circuit. The output across the diode will be constant. It is driven by a current source. As we know if the voltage across the diode exceeds a certain value it would draw excessive current from the supply. The basic diagram of zener diode as voltage regulator is given below,
To limit the current through the Zener diode series resistance R is introduced whose value can be chosen from the following equation
The above diagram is of a shunt regulators because the regulating element is parallel to the load. The Zener diode produce a stable reference voltage across the load which fulfills the criteria of regulator.