Problems of electronics, problems of physics and electronics

1. Unidirectional conductivity of PN junctions.

The p-n junction will be broken by the applied voltage and show its unidirectional conductive properties. 1. External forward voltage.

When a forward voltage is applied to the PN junction, the direction of the external electric field is opposite to that of the internal electric field, and the internal electric field becomes weaker, resulting in a narrowing of the space charge region (PN junction). At the same time, the concentration of carriers in the space charge region increases, and the resistance decreases. The applied voltage in this case is called the forward voltage or forward bias voltage, which is denoted by VF.

2. External reverse voltage.

When the reverse voltage is applied to the PN junction, the direction of the external electric field is the same as that of the internal electric field, and the internal electric field becomes stronger, resulting in a widening of the space charge region (PN junction), and a decrease in the concentration of carriers in the space charge region, and a larger resistance. The applied voltage in this case is called the reverse voltage or the reverse bias voltage, which is denoted by VR. Under the action of VR, the current through the PN junction is called the reverse current IR or the reverse saturation current IS.

This is shown in the figure below. II

I'm from the electrical department, and I think it's a bit of a hassle to explain, so I'll talk about it briefly.

It's pretty much the same upstairs.

The latter two problems are related to the working state of the transistor. The transistor can work in three states: cut-off zone, amplification zone, and saturation zone.

The signal can be amplified when working in the amplification zone.

When working in the cut-off zone, the transistor is not on, and when it is in the saturated zone, the voltage drop of the saturated transistor is 0, and the transistor is on, which is the switching characteristic.

I think if I want to learn it, I still have to read the book on analog circuits, and I can't understand a sentence or two.

This question is absolutely unclear here, and there are only two books in length, so please give me your share and buy the book for yourself. Don't waste any time, I'm serious.

I don't really understand, when I was in school, I removed one from it, like a small light bulb, but it wasn't glass, it looked like plastic. I can turn it on and turn it on. The teacher said it was called a light-emitting diode.

After graduating from the undergraduate level, the major is mainly engaged in Internet developers, or electronic engineering and technical personnel, and the corresponding industry is the communication equipment manufacturing industry, and more than 25% of the personnel are employed in state-owned enterprises, and 22% are in foreign-funded enterprises.

Although electronic science is very similar to other electronic information majors in technology, its role in the practical application stage is very limited, and it is not a universal use for the microelectronics major of the "same brother".

On the other hand, this major is not a complete research major, and if the school applied for the application is biased towards application-oriented training for students, then students will not be able to obtain a bachelor's degree in science, and it is not conducive to further study in this major.

But in reality, domain specialization and genre variability are not all bad. In China, where the mobile Internet is currently in the limelight, although the major specializes in RF circuit-related fields, it is still affected by the mobile Internet and enjoys its dividends.

In addition, the accelerated global competition for mobile signal technology has also made research talents in this field valued, and if students can obtain a bachelor of science degree in this major, they can take the fast train of 6G and other technology research and development, adding weight to their research careers.

Compared with other electronic information majors, the employment and salary of the spine are relatively weak, electronic science and technology (as far as the school is concerned, the electrical department of this college is developed from the previous semiconductor department, it seems to be quite powerful before, it seems to be the first semiconductor department in China), more biased towards materials (it seems to be to engage in chips (involving production), and another major microelectronics is a bit similar, he has to learn organic and inorganic and a bunch of ...,It seems that I still want to learn quantum mechanics.,I didn't want to learn chemistry at the beginning.,So I turned to others),Compared with the salary of other science and engineering majors,It's okay.,You can consider doing electrical preparation and systems in the future (graduate school seems to be able to consider this direction),But I think shallowly,Undergraduate education is only a general learning in a certain field.,It won't affect your future development too much.,Everyone is a family of electronics.,Undergraduate think about what you want to do in the future.,Do more experiments.,What big creations,What small creations, Or participate in more competitions (a bunch of electronic design-related ones, it would be great to win a few national awards, film it in advance), and then choose the high-paying direction of the industry at that time when you are admitted to graduate school (the big guy may be exempted).

A positively charged ball attracts a negative charge, and the negative charge in an uncharged ball shifts to the side that is close to the positive charge, so that the side that is close to the positive charge is negatively charged and the other side is charged with an equal amount of positive charge. If the two balls come into contact, the positive charge will be transferred to the uncharged ball, and the two balls will have the same kind of charge, repel each other, and will separate.

The negatively charged ball will attract a positive charge, and the positive charge in the uncharged ball will be transferred to the side close to the negative charge, so that the close side will be positively charged, and the other side will be charged with the same amount of negative charge, and after contact, the excess electrons will be transferred to the upper part, and the two balls will have the same kind of charge, repel each other, and will separate.

The positively charged ball and the negatively charged ball are attracted, the positive and negative charges accumulate in the middle of the approach, and the electrons are neutralized after contact, if the electricity is just equal, it is not charged and does not attract, if the amount is not equal, the two balls will have the same charge, repel each other, and will separate.

1.The positive charge is turned from a positively charged ball to an uncharged ball, and finally both balls are positively charged and do not separate without external force

2.In the same way as 1, it is just a negative charge transfer, and in the end they are all negatively charged, and there is no external force and they are not separated

3.Positive and negative charges are neutralized, the positive charge has a positive ball to a negative point ball, the negative charge is turned from a negative ball to a positive ball, and the amount of positive and negative charge depends on how much the positive and negative charge is after neutralization. If there is a lot of positive charge, the two balls after neutralization are positively charged, and there is no external force and they are not separated; If the positive and negative charges are equal, they will not be charged after neutralization, and the two balls will separate

Because the voltage obtained by adding z is a U-line. is a multiple of the z of the star join. The current to which z is added is i = u line z = phase z(Originally, the current was 10=u phase z).

The current of the ammeter is the combination of two currents on the switch.

i=10+(

is acting alone, us is considered a short circuit, since r2=r1, then the total current i2' = 1 2is=

US acts alone, IS is regarded as an open circuit, and the circuit resistance is left with R1 and R2 in series, i2''=US (R1+R2)=

So the branch current i2=i2'+i2''=

What is Microelectronics? Microelectronics are very close to our lives.