Why do we use Zener diodes instead of diodes?

Working principle and characteristics
Firstly, we need to understand the basic working principles and characteristics of diodes and Zener diodes. A regular diode consists of a P-type semiconductor and an N-type semiconductor, forming a PN junction. Under forward bias, the diode conducts, allowing current to pass through; Under reverse bias, the diode is turned off and the current is almost zero. However, when the reverse voltage increases to a certain extent, ordinary diodes will break down, causing a sharp increase in current, which may damage the diode.
Zener diode, also known as voltage regulator diode, is structurally similar to ordinary diodes, but has some special characteristics. Zener diodes are heavily doped to achieve higher breakdown voltage. This heavy doping makes the depletion layer of the PN junction of the Zener diode very thin, allowing breakdown to occur at lower reverse voltages. More importantly, after breakdown, the voltage at both ends of the Zener diode remains basically unchanged, which makes it suitable for use as a voltage regulator or voltage reference component.
Voltage stabilization function
The main advantage of a Zener diode is its voltage stabilization function. In circuits, voltage stability is crucial for the normal operation of electronic devices. After reverse breakdown, the current of a regular diode increases sharply, but the voltage decreases accordingly, making it unable to provide stable voltage output. After breakdown, although the current of the Zener diode varies greatly, the voltage at both ends remains stable around the reverse breakdown voltage. This characteristic gives Zener diodes significant advantages in situations where precise voltage control is required.
For example, in power circuits, Zener diodes can be used for voltage regulation and overvoltage protection. When the power supply voltage rises to the breakdown voltage of the Zener diode, the Zener diode begins to conduct, stabilizing the voltage near the breakdown voltage and protecting other components in the circuit from overvoltage damage. In addition, Zener diodes can also be used in series to achieve higher stable voltage and meet the needs of different circuits.
High speed switch characteristics
In addition to voltage stabilization, Zener diodes also have high-speed switching characteristics. In high-frequency circuits, fast signal switching is crucial for the performance and stability of the circuit. The switching speed of ordinary diodes under forward and reverse bias is relatively slow, which cannot meet the requirements of high-frequency circuits. Zener diodes, due to their unique structure and characteristics, have a fast response speed and high switching frequency. This makes Zener diodes widely used in high-frequency circuits such as communication, radar, and electronic computers.
Multiple packaging forms and adaptability
Zener diodes also have various packaging forms, such as plastic packaging, glass packaging, etc., to adapt to different working environments and installation requirements. This flexibility enables Zener diodes to be widely used in various electronic devices. For example, in electronic devices with a high degree of miniaturization and integration, plastic sealed Zener diodes are easier to install and connect; In some situations where there are special requirements for packaging form, glass encapsulated Zener diodes have more advantages.
Safety and reliability
In addition, Zener diodes are superior to ordinary diodes in terms of safety and reliability. After reverse breakdown, ordinary diodes may be damaged due to excessive current, leading to circuit failure. And the Zener diode can maintain stable voltage output after breakdown, without being damaged by excessive current, thereby improving the reliability and stability of the circuit. This characteristic makes Zener diodes more advantageous in electronic devices that require high reliability and stability.
Application examples
The application examples of Zener diodes are very extensive. For example, in photovoltaic cells, Zener diodes can serve as output current limiters to help improve the efficiency of the photovoltaic cell. In solar water heaters, a Zener diode can be used at the output end of the collector tube to prevent water from flowing back into the tube. In the radio frequency and millimeter wave radio frequency bands, Zener diodes can be used as detectors and mixers for signal reception and processing. In lasers, Zener diodes can be used to adjust the output frequency of the laser. In addition, Zener diodes are widely used in power management systems, power adapters, electronic device protection circuits, and other fields.
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