Crystal diode and transistor amplifier circuit 2

The characteristic parameters of commonly used semiconductor diodes have the following meanings:

1. Operating frequency range f (MHz): refers to the frequency range in which the diode can be applied due to the influence of P-N junction capacitance.

2. Maximum reverse voltage Vmax (V): Refers to the allowed reverse voltage across the diode, generally lower than the breakdown voltage. When the reverse voltage exceeds the allowable value, there is a risk of diode breakdown under environmental influence.

3. Breakdown voltage VB (V): When a certain reverse voltage is gradually applied to the diode, the reverse current suddenly increases, and the reverse voltage at this time is called the reverse breakdown voltage. At this point, the diode loses its rectification performance.

4. Rectified current I (mA) refers to the average rectified current of a diode during normal use.

Crystal transistor and its working principle

The transistor system is composed of two P-N junctions. According to the different combination methods, there are two types: PNP type and NPN type. Their working principles are completely identical.

There are several manufacturing methods for transistor, including growth method, alloy method, and diffusion method. Due to the complexity of the growth process and difficulty in quality control, it has been phased out. The alloy method has a simple process and low price, and is currently widely used for production. The domestically produced 3AXl-5 transistor is made by alloy method. The disadvantage of transistors made by alloy method is that the thickness of the junction is difficult to precisely control, resulting in a low operating frequency.diode

The advantage of diffusion method is that the thickness of P-N junction can be precisely controlled, and a very thin diffusion layer can be obtained, thus greatly increasing the operating frequency. The domestically produced 3AGll-14 belongs to this type and is suitable for working at high frequencies.diode