Diodes, the most basic device in electronic circuits, are indispensable on all kinds of PCB boards. I believe everyone is very familiar with them. Because of its unique unidirectional conductivity, it can guide the current forward in order like a traffic policeman standing guard on the road. We already know a lot about these common diodes, such as voltage regulator diodes, transient diodes, light-emitting diodes, etc. Today, let's explore the family of diodes in depth to see what other "capable people" there are and what unique abilities they have.
1. Tunnel diodes
Tunnel diodes use the quantum mechanics of electrons - the tunnel effect, so that electrons directly penetrate the PN junction barrier from the N layer to the P layer, generating tunnel current. It is characterized by negative resistance characteristics, its current decreases with increasing voltage, extremely high operating frequency, up to 100HZ, low power consumption, and low noise. It is often used in ultra-high-speed switching logic circuits, microwave oscillators, storage circuits, and low-noise amplifiers.
2.Step recovery diode
The step recovery diode is made by introducing a built-in electric field through uneven doping technology. After the stored charge disappears, the reverse current drops to approximately 0, eliminating the reverse current tail when turned off. Its characteristics are extremely short fall time and good forward conductivity. It can store a large amount of minority carrier charge when working in the forward direction, and the storage time when turned off is long. It can be used in frequency multipliers, high-speed pulse shaping and generators, and high-frequency harmonic generators. It can still maintain high efficiency up to 20 times the frequency multiplication, and is an excellent microwave frequency multiplication component.
3.Gold-doped diodes
Gold helps speed up the recombination of minority carriers. It can be added to the diode as a dopant to shorten its reverse recovery time. Gold-doped diodes have extremely fast recovery speeds, far exceeding other diodes. The leakage current under reverse bias conditions is small, and the diode can operate at the signal frequency even with a high voltage drop. It is mainly used in circuits that require high diode speed and low reverse leakage current.
4.Superbarrier diode
Superbarrier diode is a rectifier diode that combines the low forward voltage drop and surge handling capability of Schottky diodes with the low reverse leakage current characteristics of P-N junction diodes and high electron mobility. It has significant advantages in high power, low loss and fast switching applications.
5.PIN diode
Principle: Add a thin layer of low-doped intrinsic semiconductor layer between P and N semiconductor materials, and use its impedance characteristics of being approximately turned on or off under DC positive and reverse bias. It only presents a linear resistance to microwave signals, and the resistance value is determined by the DC bias. The resistance value is small when it is positively biased, close to a short circuit, and the resistance value is large when it is reversely biased, close to an open circuit, and does not produce nonlinear rectification effect on microwave signals. It is mainly used in the RF field and is often used as an RF switch and RF protection circuit. It can also be used as a photodiode. It is also often used in high-frequency switching, limiting, phase shifting, modulation and other circuits.
6. Avalanche diodes
Working on the principle of avalanche breakdown, under reverse bias conditions, the P-N junction is ionized, resulting in a large current. Specially designed to break down at a specific reverse voltage to prevent damage. It can be used as an RF noise generator, an RF source for antenna analysis bridges, a white noise generator, and can also be used in radio equipment and hardware random number generators, microwave frequency generators, etc. It can also be made into a single photon avalanche detector, a high-gain photon detector for light-level applications.
