The role and application of Schottky diodes

application:

The structure and characteristics of SBD make it suitable for high-frequency rectification in low-voltage and high-current output occasions. It is used for detection and mixing at very high frequencies (such as X-band, C-band, S-band and Ku-band). Used as a clamp in high-speed logic circuits. SBD is also often used in ICs. Like SBD? TTL integrated circuits have long become the mainstream of TTL circuits and are widely used in high-speed computers.

In addition to the characteristic parameters of ordinary PN junction diodes, SBD electrical parameters used for detection and mixing also include intermediate frequency impedance (referring to the impedance presented by the SBD to the specified intermediate frequency when the rated local oscillator power is applied, generally between 200Ω and 600Ω) , Voltage standing wave ratio (generally ≤ 2) and noise figure, etc.

effect:

Schottky diode Schottky diode, also known as Schottky barrier diode (SBD), is a low-power, ultra-high-speed semiconductor device. The most notable feature is that the reverse recovery time is extremely short (can be as small as a few nanoseconds), and the forward voltage drop is only about 0.4V. It is mostly used as high-frequency, low-voltage, high-current rectifier diodes, freewheeling diodes, protection diodes, and also useful as rectifier diodes and small-signal detector diodes in circuits such as microwave communications. It is more common in communication power supplies, inverters, etc.

A typical application is in the switching circuit of a bipolar transistor BJT. By connecting a Shockley diode to the BJT to clamp, the transistor is actually close to the off state when it is on, thereby increasing the switching speed of the transistor. This method is a technique used in the TTL internal circuits of typical digital ICs such as 74LS, 74ALS, and 74AS.

The biggest feature of Schottky diodes is that the forward voltage drop VF is relatively small. In the case of the same current, its forward voltage drop is much smaller. In addition, its recovery time is short. It also has some shortcomings: the withstand voltage is relatively low, and the leakage current is slightly larger. It must be fully considered when selecting.