Analog Integrated Circuits in the Information Age

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Analog Integrated Circuits in the Information Age

Peng Huizhong

With the rapid development of information technology and its industry, today's society has entered a brand new information age. Microelectronics technology is the core technology of information technology, and analog integrated circuits (IC) are one of the core technologies of microelectronics technology. Therefore, analog IC has become an important technical development goal in the information age. Analog IC includes circuits with pure analog signal processing functions and circuits with A-D mixed signal processing functions. Its technical scope involves data converters (such as A-D, D-A converters, etc.), linear and nonlinear amplifiers (such as operational amplifiers, radio frequency amplifiers, logarithmic amplifiers, voltage comparators, analog multipliers, etc.), electronic switches and multiplexers, voltage regulators (such as linear voltage regulators, switching power supply controllers, etc.) and other analog ICs (such as drivers, delay lines, sensors, etc.). Analog IC is mainly used to complete the functions of collecting, amplifying, comparing, and transforming analog signals. The relationship between it and digital circuits and A-D, D-A conversion circuits was discovered by Paul R. of the University of California as early as 1986. Professor Gray's so-called "egg model" gives a vivid description. The model regards the three of them as an egg, and the digital circuit as the yolk, the analog circuit as the eggshell, and the A?D, D?A circuit as the egg white. The three are not the same, but also a unified organic whole. After the various analog information in the real world is collected, amplified, and transformed by analog IC, the signals required for computer or digital circuit processing can be obtained, thereby realizing the information products people need. Obviously, analog IC is a bridge between the analog world and the digital electronic information system. When analog IC processes analog signals, most of them work in the small signal state except for the power output stage. The signal frequency often extends from DC to high frequency. Its operation is obviously different from the switching state when the digital circuit processes the signal. In addition, analog ICs are of various types, complex functions, and huge performance differences. Therefore, analog ICs have distinct personalities that are different from digital circuits in terms of manufacturing process, device structure, circuit architecture, etc., which are mainly manifested in: analog ICs must have good current amplification characteristics, low current characteristics, frequency characteristics, etc. in the entire linear working area; in design, due to the needs of technical characteristics, the symmetrical structure of component layout and the matching form of component parameters are often considered; due to the limitations of process technology, resistors and capacitors should be used as little as possible or not at all during design, especially high-resistance resistors and large-capacity capacitors; many analog circuits require power output, so the power supply voltage is relatively high; the degree of design automation is low, the CAD tools and design parameter libraries are highly accurate, the process is highly specialized, the process line varieties change frequently, and the process control is difficult, etc. Therefore, the core technologies of analog ICs mainly involve high-speed technology, high-frequency technology, low-noise technology, high-voltage technology, low-power technology, high-power technology, etc. In order to meet various technical requirements, circuit design and process processing must be well coordinated. The main developments of single-chip process technologies for analog ICs include bipolar, BiCMOS, CMOS, and SiGe, among which bipolar and BiCMOS processes are more commonly used. With the improvement of CMOS technology, there is a trend towards CMOS in the processing technology of analog and digital mixed circuits. Among analog ICs, the process level of most high-speed analog ICs is about 0.5 microns, and the process level of general analog ICs is 1-3 microns. In terms of advanced processes, 0.1 micron technology has been developed. In terms of devices, due to the wide variety of application requirements for analog ICs, not only more than ten major categories of analog IC products have been developed, but also hundreds and thousands of products have been developed for each type of analog IC. There are all kinds of products and performance levels to meet the different needs of applications. Among them, the data converter is an analog and digital mixed signal processing circuit, and its analog circuit part occupies more than 50% of the chip area. In terms of data converters, 8-14-bit 1-80MHz high-speed A?D technology is very mature, and there are sufficient products. A?D converter products with 16 bits and above 30MHz can also be seen. At the same time, in A?D converters, not only analog ICs with integrated functions appear, such as multiplexers, instrument amplifiers, sampling amplifiers and other A?D converter subsystems, but also other analog ICs and various digital circuits such as DSP, memory, CPU, I?O, etc. will continue to be integrated together. Data converters are widely used. For example, the high-performance and low-power A?D converters launched by National Semiconductor (such as ADC10321? with 10-bit resolution, 20MHz sampling speed, single power supply operation) can be widely used in digital set-top boxes, cable modems and CCD input systems. Amplifiers are currently mainly made using bipolar technology. Although CMOS amplifiers have advantages in power consumption and size, they are too expensive and their applications are limited. In terms of RF amplifiers, SiGe bipolar technology is being used to meet the high-performance requirements of applications. Amplifiers are currently being used in various handheld communication devices, which require low power consumption. ADI (Analog Devices)'s high-performance amplifier series (such as AD8350, which operates at 1200MHz and has a noise figure of 6.1dB at 250MHz, with a high dynamic range, excellent linearity and common-mode rejection) can be effectively used in communication transmitters and receivers, general gain amplification systems, A/D buffers, high-speed data interface drivers, etc. ADI has also developed amplifiers with high comprehensive levels in bandwidth, power consumption, distortion and driving capabilities, such as AD8014, which is an ultra-high-speed amplifier with a 400MHz-3dB bandwidth, a 4000Vms slew rate, a 24ns settling time, extremely low voltage and current noise, and low distortion, and can be ideally used in broadband signal processing. According to the statistics of the world IC market development trend by the market research company ICE, the market share of analog IC in the total IC product market is: 16% in 1993 (the total IC market is 68.18 billion US dollars), increased to 17.5% in 1998 (the analog IC market reached 19.1 billion US dollars), and will still be close to 15% in 2002. It can be seen that the stable development of the market has greatly reduced the instability and risk of production by manufacturers. Since China's reform and opening up, the information product manufacturing industry has formed a relatively complete industrial production system. Facing the challenges of the new century, China will continue to adopt national policies to vigorously support the development of the information industry and create a better technology development environment, which has brought excellent opportunities for the development of IC. We must seize the opportunity, continuously push China's analog IC technology to a new level, and create new contributions to the development of the information society. ( http://www.newmaker.com )