Chapter 846 The secondary structure is good
This thing was almost completely eliminated later, and only a few places are still using it, such as HiFi, because after this thing is closed, it behaves like a resistor in the circuit, with very good linearity, and it works well when used in audio.
Otherwise, the money of HIFI is easy to make, and the money of the junk guy for a penny is hard to make.
General Cui nodded. This thing is indeed low in cost. It can be really used a little bit. At least it is much smaller than the relay, and the price is low.
"If you want to be at a high speed, I just took into account a possibility. With the light and electrical diode as a sensitivity, the optical diode switching speed is fast." Cui continued to discuss his thoughts with Gao Zhendong.
With proper design, photodiodes have extremely fast switching speed. If we talk about switching speed, Mr. Cui really can't think of anything faster than it.
I have to say that these senior technical personnel have several brushes.
Gao Zhendong nodded: "The speed of the optoelectronics diode is indeed fast, but there is a problem with the optoelectronics diode, which determines that its scope of application is limited."
There are disadvantages when there are advantages. There are no shortcomings. It is estimated that there will be expensive disadvantages.
"Mr. Gao, what do you mean?"
"The current conversion ratio of the photodiode is too low. If you calculate it carefully, you will know that based on the current technical conditions, it is only a few thousandths. Because it is a passive device and relies entirely on the energy of that light to generate current. The luminous efficiency , photoelectric efficiency and other reasons determine that its current conversion ratio is not large. ”
The current conversion ratio, the ratio of the input current of the control terminal to the output current of the controlled terminal, can actually be understood as an amplification factor.
Different from the use of triode and other methods, the only source of energy for the optoelectronics diode is the beam of light opposite.
"Do you believe in light?", "Believe! Don't believe it."
Under this condition, the current conversion ratio of the photodiode alone will not look good no matter what method is used.
"Gao Chief, I remember that we also seem to have made solar panels, and there are several percentage points of efficiency?" Some comrades asked, although it was also very low, but there were still several levels of order than a few thousandths.
I know this, and I know it very clearly. Gao Zhendong smiled and shook his head: "The structures of solar panels and photodiodes are different. They are incomparable. Moreover, there is a light source at the optocoupler. What’s the problem with luminous efficiency?”
Listen to it, the current was peeled twice during the lighting and light sensing stage, and the result was naturally not good -looking.
However, Gao Zhendong did not completely deny this idea, because Mr. Cui's idea solved at least half of the problem.
"But what you said is a benefit that provides a very fast switching speed basis. If you add appropriate amplifying output circuits behind it, you can get good output parameters with the output of the light diode."
Knowing that everyone has doubts about the switching speed of the power stage, Gao Zhendong added.
"Although the speed -coupled switch speed at this time depends on the switch speed of the amplifier circuit, at least at this time we can concentrate the problem to solve the speed of this amplifier. With different amplifiers Moreover, these things can be integrated into a silicon wafer. Although it is a two -level structure, in fact, the device is only a whole piece, which is very good for manufacturing.
Gao Zhendong directly gave his ultimate answer.
The front-stage photodiode at the output end is used as a switch, and the rear stage is added with an ordinary triode or other amplification circuit, and good results can also be obtained.
And at this time, as long as the switch speed of the triode goes up, the speed of the natural electronic switch is also up. In fact, the ultimate form of optocoupler -solid -state relay is such a structure.
It's just that the realization of solid-state relays requires another thing, but without this thing, Gao Zhendong can also make a usable electronic switch. After all, it can be called a relay, which is different from ordinary electronic switches. It is normal to have a certain threshold.
Mr. Cui nodded repeatedly: "Well, the structure you proposed is good, and I suddenly understood. First, a diode is used to provide the basic switching speed, and then the post-amplification circuit is used to determine the specific performance. This solves a problem, good , great.”
The comrades in Factory 1218 also had their own thoughts. One comrade felt that this was a bit like taking off his pants and farting. "General Engineer Gao, can you directly use phototransistors to perform photosensitive switching? In this case, the structure of the output pole can be simpler."
The optoelectronics diode drives the triode, it must not be convenient to get a photovoltaic triode directly.
Gao Zhendong was very happy. This thing seemed true at first glance, but in fact it was not that simple.
He did not laugh at the comrade. He thought about it, but he couldn't understand it by himself. This kind of triode structure did have it, but Gao Zhendong did not choose.
"Theoretically, you are right. Optical triodes can indeed achieve this effect, but in fact it complicates things because optical triodes are more difficult to manufacture than separate photodiodes and post-stage triodes. They can provide better overall performance , it is not as good as this two-level structure that performs its own duties. I chose this structure based on the technical difficulty and prospects.”
Solid-state relays ultimately use this secondary structure, but they use special post-amplification devices. This is not without reason.
Being able to get the general worker in theory, this comrade is still very happy and happy. As for actually his own thoughts are not thoughtful, what is it?
Other comrades also had the same idea as him, but they just didn't have the time to say it or didn't have time to say it. But after listening to Gao Zhendong's explanation, they understood it.
The phototransistor integrates optoelectronics and amplification. The design and manufacturing of the phototransistor itself becomes more difficult. It is integrated and structurally integrated into a whole. It is very troublesome to take into account various parameters. It seems The high degree of integration is actually far less convenient than this secondary structure.
Suitable photodiodes and post-amplification circuits are basically ready-made now, but suitable phototransistors are not available yet. Introducing too many new things will have a great impact on the successful completion of the project.
There is no mistake in every song, one post, one content, one 6 one, one book, one book, take a look!
Gao Zhendong, who has limited resources, directly chooses this method which is relatively less difficult but has better actual development prospects, and there is not much difference in production costs.
In terms of semiconductor processing, there is not much difference between making a diode + transistor and a phototransistor on a silicon wafer. Even phototransistors may have higher processing costs at this stage due to more requirements and greater restrictions.
"Another reason is that the characteristics of the optocoupler in the phototransistor structure are limited by the triode itself. When a new type of triode appears, the phototransistor must be redesigned for this triode. This is a very troublesome thing. But for the secondary structure, it is actually much simpler to replace the subsequent stage, and the performance of the latest amplifier device can be obtained as quickly as possible,” Gao Zhendong said with a smile.
Anyone or a special tube or a special tube, theoretically replace the rear level directly.
President Cui has been heard here, and he just shot his thighs: "Yes! Too right! Gao Chief, you are not only theoretical proficiency, open -minded, but also for specific work and research routes.
This is not him. He just had the choice of the structure of the optocoupler in the optocoupler. After some words, he opened it and buckled it in. He also considers the performance and the difficulty.
Regarding the ability of Gao Gao workers, I used to look at it from a distance. I did not participate in the specific work process. It didn't feel it, but now he and Pan Fang Director really feel that the chief worker is prestigious in the 12th machine department. This experience and thinking are really incredible.
Gao Zhendong was a little embarrassed. He was making choices based on the answers, and he was naturally much better than all of them.
What? Is the system your own? Have the results brought tangible benefits to society and the masses? That's okay, copy it hard for me!
General Manager Cui quickly clarified the next things to do in this work in his factory: "General Manager Gao, I think so, then we will first use LED light sources as the basis to develop photosensitive Resistive optocoupler, and photodiode output post-amplification optocoupler. For the latter's amplification stage, we first use high-speed ordinary triodes. At least we can get through it in principle first, and we can also get a batch of basically usable devices. .”
The benefits of using a secondary structure can already be seen from his current arrangement. Now it requires high-speed switching, right? Then use the fastest triode as the post-amplifier. As long as other parameters can be used, get one first and try it out.
Even General Cui has now seen the prospects from this structure, and changing the back stage is a distinctive new device!
The method of high -chief workers is to bring all kinds of optocouplers.
Gao Zhendong nodded in agreement: "Well, your idea is good, and you don't have to worry. The target installation equipment for this switch still has a long research journey to go. Let's work slowly and steadily. By the way, remember, it's best It is a one-way communication and a two-way communication.”
Ordinary transistors are directional and have only one conduction direction. However, for program-controlled switches, Gao Zhendong wanted to make bidirectional transistors in one step, which would reduce some work restrictions for the comrades of the Institute of Communications.
"Well, that's easy to say. I can just use two transistors back to back, but this will further deteriorate the linearity. Is there any problem?" Mr. Cui's basic thinking about components is still very comprehensive. Speaking of linearity, I think of photoresistor again, but unfortunately that thing is too slow.
(End of chapter)