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t's about the transformation and development of RF engineers

Click:133 Time:2020-08-20 09:21:01

Now graduate students are studying, doing antennas, and are more interested in radio frequency and radio frequency integration (a part of microelectronics). I want to ask a few questions like this.


1. In the future, the trend of circuits is digital and integrated. So, will the living space of traditional RF engineers, including those who make devices and the design of RF front-ends, be compressed? What is the way out for traditional RF and microwave engineers?


2. If it is a device or antenna to IC, there is no actual engineering foundation for making chips. Apart from reading "Microwave Engineering" and Razavi's textbooks, how to shorten the gap with the industry.


@李一雷:


1.Traditional microwave engineers use discrete devices to build radio frequency systems, that is, board-level design (as opposed to IC). The trend of future radio frequency systems (for example, below 30 GHz) is that in ordinary commercial radio frequency systems, the radio frequency components on a PCB board include antennas, T/R switches, PA and SoC (including LNA, mixer, PA driver and other radio frequency modules and PLL, Baseband and other digital/analog modules). Antenna, T/R switch and PA are difficult to integrate on a chip, so they will be separated from SoC.


Around the beginning of the 21st century, academia headed by Asad Abidi began to study CMOS RF, and RFIC began to become popular in the industry, causing RF systems to tilt toward IC. This wave of trends has basically reached saturation so far, that is, the positions of board-level RF engineers should not be reduced (because antennas and T/R switches are difficult to be integrated on-chip). Therefore, the future prospects of being a traditional RF engineer will not be worse than today's salary.


2. From device/antenna to RFIC, if you can really get through the two books of Pozar and Razavi, it is really enough for a graduate student. There are currently two perspectives for RFIC. One is to treat RF circuits as high-speed analog circuits like Razavi and Abidi, without considering impedance matching, transmission lines, S-parameters, etc. The other school starts with traditional microwaves and regards RFIC as a discrete device integrated on a chip. In fact, these two perspectives are indispensable. Only when they are truly integrated can one be a qualified RF engineer. So if you can integrate Pozar's "Microwave Engineering" and Razavi's "Radio Frequency Microelectronics" (preferably the second edition) before graduation, you will be better than 80% of the master's students doing RF in the country. In addition to reading books, you can actually design some circuits and walk through the process (Cadence Composer for circuit design/SpectreRF for circuit simulation/Virtuoso for layout/Calibre PEX for parasitic parameter extraction and post-simulation). After you actually do a few circuits, the gap between you and the people in the industry may just be your experience in tapeout/testing.


@LeonMac:


1. Traditionally, the technical analysis of antennas is basically based on the concept of "field" (such as radiation field, gain, pattern, etc.); while the technical basis of RF circuits (including RF IC) is generally based on "Comes from the concept. From a micro perspective, the analytical methods and theoretical basis of the two are not exactly the same. But the core theoretical foundation is still interoperable. From a professional level, the antenna field theory is more professional-it is less difficult to transfer to the circuit field;


2. From a purely professional development perspective, the antenna direction is indeed narrower, mainly because it is too specialized. In fact, the domestic civil antenna field generally uses mature antenna products without special in-depth technical accumulation; the real antennas are still in military and research institutes; from this perspective, the antenna direction is indeed narrower. Unless you are a master. In other words, any industry expert is a scarce resource, right? Pulled away.

RF IC is a good direction. On the macro level, it is still a shortcoming of our celestial dynasty in the foreseeable future. The government will vigorously develop it, and the market will also have this demand. In addition to the necessary high-frequency circuit analysis and EMI analysis, we also need to involve some knowledge of integrated circuits.


The work of RF board-level circuits, because RF ICs are becoming more and more integrated and digitized and software-based, and more systematically developed-in most cases, the so-called RF board-level circuits are the work of layout and testing. Experience in this field Accumulation is more important than theoretical knowledge, and the understanding of communication systems is more important than pure RF circuit knowledge itself.


3. Regarding the accumulation of knowledge, my opinion: you can't become a master simply by reading books or listening to lectures--even if you have a thorough understanding of the theoretical formula, you can derive it freely. If you don't know how to deal with practical problems, it's just a matter of fact--so find a suitable one The position that can meet your development expectations (provide more practical opportunities, the more the better) is the best choice.


4. If you want to change your major as early as possible-you need at least 5 years of practical experience in any field to become an expert. So don't miss it if you decide. But before deciding to ask yourself, if you don’t like technology that much (do you look at the prospects or the money scene), just do it casually, try more different fields (each field at least 2 years) and then transfer to the market or business. Way out.


@卢黎:


1. Now, the trend of radio frequency is indeed discrete to on-chip transformation is obvious. But the antenna is still a more important discrete component, and it is not so good to replace.


2. If it is purely an antenna, the employment area is a bit narrow. After all, antennas are very specialized fields, and sometimes it is not easy to jump in a city if you want to change jobs. My junior is a good example. Of course, being an expert is also a way, just keep going.


3. Switching to IC is one direction. After all, you have a background in microwave, so it is estimated that you haven't made many boards as antennas. But if you choose one or do some board RF direction, you should get started quickly.


4. Hardware programming is also a good direction now. If the software foundation is not bad, FPGA and instrument programming are all good ways.


In short, it is more difficult to send radio frequency, but in such a professional field, as long as it is done steadily, food and clothing will not be a problem. And now rf has entered more fields with communication, and there is a lot to do in cross-fields :)


@Research left-behind children:


My Ph.D.'s direction is to work on microwave and millimeter waves. Let me start with the conclusion: I think the demand and development prospects of RF system engineers are still great. According to my professional understanding of microwave, the microwave direction can be roughly divided into three directions: 1) passive (antenna, filter, etc.) 2) active circuit (radio frequency circuit, and various board-level circuits such as PA, LNA, etc.) ) 3) Make chips (focus on device level, such as power amplifier, mixer, low noise amplifier, etc.).


Let me talk about the direction of chips first. Chips seem to be relatively high-end, but in fact, China is far from developed countries in this respect. There are not many domestic chip design positions (compared to radio frequency). Domestic chip companies are mostly small and medium-sized companies, and there are not many jobs. The chip industry has large investment, expensive equipment, expensive process lines, and process blockade. The process lines generally used in China are those that were eliminated from abroad ten years ago. 


Chips designed by small and medium-sized companies that make chips often have to be shipped abroad, and the tape-out cycle is long. In terms of overall performance, it is not as good as a large foreign company. It is a long way to think of large companies like foreign ADI, TI, MINI CIRCUITS in China. The chips mentioned above are only radio frequency or millimeter wave chips. For baseband chip design (FPGA), China may have a longer way to go. Therefore, the main employment in the chip direction is to go to small and medium-sized start-up companies or specific research institutes (55 or the like), and the salary of students with better chip design is still very attractive.

Let me talk about the direction of radio frequency:


1.First of all, I think it must be a trend that the chip integration is getting higher and higher. But these are for applications with a wide range of users, such as mobile phones, sub-6G, or millimeter-wave vehicle radars that have become popular in recent years. In other words, if the application does not reach a certain level, an integrated chip will not be introduced (the R&D cost is not worthwhile compared to the revenue). For example, the large phased array radars designed by the research institutes of CLP have a set of indicators for one radar, and the requirements for indicators are often very high. Can you expect to use a large-scale multi-channel general integrated chip to do it?


2. Secondly, the radio frequency system is not simply finished by connecting the chips with 50 ohm wires. The higher the frequency and the number of channels, the system will encounter a lot of problems, and there are many detailed problems that need to be dealt with. The same scheme is given to different people, and the performance may be quite poor. For example, simply cascading two chips together is likely to self-excite and not work without a good power amplifier. There are also various coupling problems with high frequency, how to filter out the signal spurs that are too large and not up to standard. The datasheet of a single chip testing company feels very good and it is often wrong to connect them together. A large part of the value of the RF engineer lies in the experience of debugging and solving practical problems. The more experience you accumulate, the greater your value (try not to make a special drawing board). I’m here at Dongda University, and I have observed that every year when master students graduate, they have a little understanding of radio frequency. You can prepare for graduation by making two small boards. It is relatively easy to go to Huawei (16*16k). If a doctoral student here does not go to a university, it would be nice to go to a research institute.


3. Then, it is not a concept for the RF system engineer to be a front-end board alone. The front-end board is likely to be a board. The system engineer must also consider the structure, power consumption, installation, heat dissipation, back-end data processing, and baseband program. , Test scenario construction, test program, etc. There are many things to learn in these processes, and these things are often not well understood by those who design chips individually.


In summary, the demand for RF engineers in China is far greater than the demand for chips, and most companies do not have the conditions to develop their own chips. The main market for research and development of chips is monopolized by major international companies. China is growing but there is still a considerable gap between it and foreign countries. Even if the chip is integrated, there are still many problems that need to be solved by him as an RF system engineer. Large companies like Huawei still mainly recruit RF engineers. And if you are a master's student, then the short school system will not have time to get in touch with good chips. If you are interested in chip design and have the opportunity to contact chip design, you can also devote yourself to the chip business and do well.


@Chris:


Personal opinion, let’s accumulate technology first. RF circuit experience is very important. PCB design and RF module debugging require the accumulation of time and experience. Please refer to the design information of relevant RF modules and products within or outside the company and participate more. Product debugging, the use of test equipment by RF engineers is the most basic, and testing and debugging methods also require the accumulation of specific project experience. Don't pick specific work content first, any work content can let you learn technology in the early stage.


After a certain amount of technology accumulation, we must consider the general working direction in the future. There are probably receiving channels, power amplifiers, frequency synthesis, passive components including filtering, etc. There is also an antenna design direction that is not related to the circuit, and there is also an overall system optimization. . At present, due to the increasing integration and performance of RF chips, small-signal RF design is relatively simple, just buy a mature chip and use it. High-power RF and microwave power amplifiers are the final choice of many RF engineers, because Products with too much power are difficult to achieve single-chip integration, so there is still room for RF engineers to play. It is a challenge to improve the power and efficiency of the power amplifier. I personally think that the entire radio frequency transceiver system requires in-depth study and research to allow radio frequency engineers to go further.


After being familiar with the entire radio frequency system, the career of radio frequency engineer should also be taken to a higher level. Starting to be responsible for the research and development of the entire product radio frequency system, it is basically a small head of a department. Going up is the high-level work content of product definition, mass production optimization, etc., basically reaching the level of department manager. Going further depends on personal opportunities and accumulation.


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