1. Classification and characteristics of analog op amps Analog op amps have been around for more than 40 years since their inception. The earliest process was a silicon NPN process, which was later modified to a silicon NPN-PNP process (hereafter referred to as the standard silicon process). After the junction FET technology is mature, the junction FET process is further added. When the MOS tube technology matures, especially after the CMOS technology matures, the analog operational amplifier has a qualitative leap. On the one hand, it solves the problem of low power consumption. On the other hand, through the hybrid analog and digital circuit technology, it solves the direct small-signal signal directly. Handling puzzles. After years of development, the analog operational amplifier technology has been very mature, the performance is perfect, and there are many varieties. This makes it easy for beginners to choose. In order to facilitate the selection of beginners, this paper uses two classification methods, such as process classification and function/performance classification and classification, for the integrated analog operational amplifier, which is easy for the reader to understand and may be different from the common classification method. 1.1. Classified according to manufacturing process According to the manufacturing process, the integrated analog operational amplifiers currently in use can be divided into standard silicon process operational amplifiers, operational amplifiers incorporating a junction FET process in a standard silicon process, and operational amplifiers incorporating a MOS process in a standard silicon process. . According to the process classification, it is for the beginners to understand the influence of the processing technology on the performance of the integrated analog operational amplifier, and quickly grasp the characteristics of the operational amplifier. The integrated analog op amp of the standard silicon process features low open-loop input impedance, low input noise, low gain, low cost, low accuracy, and high power consumption. This is because the integrated analog op amps of the standard silicon process all use NPN-PNP tubes. They are current-type devices with low input impedance, low input noise, low gain, and high power consumption, even if the input stage is improved by various techniques. Under the premise of taking into account the abilities of the device, it is still impossible to get rid of the problem of low input impedance. The typical open-loop input impedance is on the order of 1M ohm. In order to take into account the frequency characteristics, the intermediate gain stage should not be too large, so that the total gain is small, generally between 80 and 110 dB. The standard silicon process can be combined with laser correction technology to greatly improve the accuracy of the integrated analog operational amplifier, and the temperature drift specification can now reach 0.15ppm. Universal op amps and high-speed op amps can be designed by changing the standard silicon process. A typical representative is the LM324. The operational amplifier that incorporates the junction FET process in the standard silicon process is mainly to improve the input stage of the integrated analog operational amplifier of the standard silicon process into a junction FET, greatly improving the open-loop input impedance of the op amp, and improving the general purpose. The op amp's conversion speed is similar to other integrated analog op amps in standard silicon processes. Typical open-loop input impedance is on the order of 1000M ohms. A typical representative is TL084. The operational amplifiers incorporating the MOS FET process in the standard silicon process are divided into three categories. One is to improve the input stage of the integrated analog operational amplifier of the standard silicon process to a MOS FET, which is much larger than the junction FET. Increase the open-loop input impedance of the op amp, along with the conversion speed of the general-purpose op amp, similar to the integrated analog op amps of standard silicon processes. Typical open-loop input impedance is on the order of 10^12 ohms. A typical representative is CA3140. The second type is an analog operational amplifier using a full MOS FET process, which greatly reduces power consumption, but the power supply voltage is reduced and power consumption is greatly reduced. Its typical open-loop input impedance is on the order of 10^12 ohms. The third type is an analog-digital hybrid operational amplifier using the full MOS FET process. It uses the so-called chopper-stabilization technology, which is mainly used to improve the processing accuracy of DC signals. The input offset voltage can reach 0.01uV, and the temperature drift index can be reached at present. 0.02 ppm. Close to ideal op amp characteristics in handling DC signals. Its typical open-loop input impedance is on the order of 10^12 ohms. A typical product is the ICL7650. 1.2. Classified by function/performance This classification method refers to the integrated operational amplifier of China Integrated Circuit Encyclopedia. According to function/performance classification, analog operational amplifiers can be generally divided into general-purpose op amps, low-power op amps, precision op amps, high-impedance op amps, high-speed op amps, broadband op amps, high-voltage op amps, and some special Op amps, such as programmable op amps, current op amps, voltage followers, and more. In fact, there are many types of op amps in order to meet the needs of the application. This article is based on the above simple classification method. It should be noted that as the technology advances, the threshold of the above classification has been changing. For example, the previous LM108 was originally classified as a precision op amp and can only be classified as a general-purpose op amp. In addition, some op amps have both low power and high input impedance, or similar, so that they can be classified into multiple classes at the same time. A general-purpose op amp is actually the cheapest op amp with the most basic functions. These types of op amps are versatile and use the most. Low-power op amps reduce power consumption based on general-purpose op amps and can be used in places where power consumption is limited, such as handheld devices. It has low static power consumption, low operating voltages close to battery voltage, and good electrical performance at low voltages. With the advancement of MOS technology, low-power op amps are not an individual phenomenon. The static power consumption of low-power op amps is typically less than 1mW. Precision op amps are integrated op amps with very low drift and noise, high gain and common mode rejection ratio, also known as low drift op amps or low noise op amps. The temperature drift of such op amps is typically less than 1 uV/degree Celsius. Due to technological advancement, the offset voltage of some early operational amplifiers is relatively high, which may reach 1mV; now the offset voltage of precision op amps can reach 0.1mV; the offset voltage of precision op amps using chopper-stabilized technology can reach 0.005mV . Precision op amps are mainly used in places where the accuracy of the amplification process is required, such as self-control instruments. A high input impedance op amp generally refers to an integrated op amp that uses a junction FET or MOS transistor as the input stage. This includes an integrated op amp made of a full MOS tube. The input impedance of a high input impedance op amp is typically greater than 109 ohms. A side feature of high input impedance op amps is the high conversion speed. High input impedance op amps are used in a wide variety of applications such as sample and hold circuits, integrators, log amps, measurement amplifiers, bandpass filters, and more. A high-speed op amp is an op amp with a high conversion speed. The general conversion speed is above 100V/us. High-speed op amps are used in high-speed AD/DA converters, high-speed filters, high-speed sample and hold, phase-locked loop circuits, analog multipliers, confidential comparators, and video circuits. At present, the highest conversion speed can already achieve 6000V/us. A broadband op amp is an integrated op amp with a much wider -3dB bandwidth (BW) than a general-purpose op amp. Many high-speed op amps have a wide bandwidth and can also be called high-speed broadband op amps. This classification is relative, and the classification of the same operation under different conditions of use may vary. Broadband op amps are primarily used to process circuits with wide bandwidths of input signals. High voltage op amps are designed to address high output voltage or high output power requirements. In the design, it mainly solves the problem of voltage withstand voltage, dynamic range and power consumption of the circuit. The high voltage op amp's supply voltage can be higher than ±20VDC and the output voltage can be higher than ±20VDC. Of course, a high-voltage op amp can be replaced by a general-purpose op-amplifier transistor/MOS transistor. 35 Kv Transformer,Low Noise 35 Kvoil-Immersed Transformer,Oil Immersed Transformers With High Load Capacity,High Voltage Insulated Oil-Immersed Transformer Tianhong Electric Power Technology Co., Ltd , https://www.tianhongtransformer.com