Digital potentiometer, also known as numerical control device, is a new type of CMOS integrated circuit for mixed digital and analog signal processing. The digital potentiometer is controlled by digital input and generates analog output.   According to different digital potentiometers, the maximum tap current can range from hundreds of microamps to several milliamps. The digital potentiometer adopts numerical control to adjust the resistance value, which has the remarkable advantages of flexibility, high adjustment accuracy, no contact, low noise, not easy to damage, anti vibration, anti-interference, small size, long service life and so on. It can replace the mechanical potentiometer in many fields.   Potentiometer is an adjustable electronic component. It is composed of a resistor and a rotating or sliding system. When a voltage is applied between the two fixed contacts of the resistance body, the position of the contact on the resistance body is changed by rotating or sliding system, and a voltage that is certain to the position of the moving contact can be obtained between the moving contact and the fixed contact.   Potentiometer is a resistance element with three leads, and the resistance value can be adjusted according to a certain change law. Potentiometers usually consist of resistors and movable brushes. When the brush moves along the resistance body, the resistance value or voltage that is related to the displacement is obtained at the output end.   The potentiometer can be used as either a three terminal element or a two terminal element. The latter can be regarded as a variable resistor. Because its function in the circuit is to obtain an output voltage that is related to the input voltage (applied voltage), it is called a potentiometer.   In terms of application scope, digital potentiometers are rapidly promoted at home and abroad, and are widely used in detection instruments, PCs, mobile phones, household appliances, modern office equipment, industrial control, medical equipment and other fields. For example: refrigerator, programmable computer, power supply, power meter, automatic detection equipment, optical fiber network, adjusting LCD display, voltage control, replacing mechanical potentiometer, matching linear impedance, adjusting VCOM settings.

Capacitors are energy storage elements used in circuits for tuning, filtering, coupling, bypass, energy conversion, and delay. Capacitors are often called capacitors. According to its structure, it can be divided into three types: fixed capacitor, semi-variable capacitor and variable capacitor.   Solid aluminium electrolytic capacitor is short for conductive polymer solid aluminium electrolytic capacitor, and is one of the highest-grade products in capacitor products.   ESR (Equivalent Series Resistance) refers to the series equivalent resistance, which is an important indicator of capacitance. The lower the ESR, the faster the charge and discharge of capacitance. This performance directly affects the decoupling performance of power supply circuit of microprocessor. The advantage of low ESR of solid-state electrolytic capacitance in high frequency circuit is more obvious.   It can be said that the low ESR characteristics at high frequencies are the watershed between the performance differences of solid electrolytic capacitance and liquid capacitance. The ESR of solid-state aluminium electrolytic capacitance is very low, with very small energy dissipation. The very low ESR characteristic of the solid state capacitor under high temperature, high frequency and high power conditions can fully absorb the high amplitude voltage generated between the power cords in the circuit and prevent its interference to the system.   Currently, the power consumption of the CPU is very large, the main frequency is far beyond 1GHz, the peak current of the CPU reaches 80A or more, and the output filter capacitance is close to the critical point of operation. On the other hand, CPUs work in a variety of modes, most of the time in the process of working mode conversion. When the CPU changes from a low power state to a full load state, the large amount of energy required for instantaneous (generally less than 5ms) switching of this CPU comes from the capacitance in the CPU power supply circuit. At this time, the high-speed charging and discharging characteristics of the solid state capacitor can output the high peak current instantaneously, ensuring adequate power supply and ensuring the stable operation of the CPU.

Crystal oscillators can help electronic systems provide frequencies for synchronous operation, as frequency references or to achieve accurate timing.   In microprocessor-based systems, there are several different frequency signals used to execute instructions, move data into and out of memory, and external communication interfaces.   A simple embedded controller may have a clock frequency of several MHz, while microprocessors in personal computers usually expect an input frequency of 15 MHz. This will multiply internally to provide the frequency of the CPU and other subsystems. Other components in the system may have their own frequency requirements.   In addition to providing the basic requirements of the specified frequency, the oscillator may have to meet other requirements depending on the application requirements of the product.   For example, many product applications require extremely precisely defined frequencies. This is particularly important for systems that need to communicate with other devices through serial or wireless interfaces. Accuracy is usually measured in parts per million (PPM).   At the same time, the trimming circuit can be based on resistance capacitance (RC) or inductance capacitance (LC) networks. These devices are relatively simple and can change the frequency in a wide range. However, designing an accurate RC oscillator or LC oscillator requires the use of expensive precise components. Even so, they cannot meet the highest accuracy and stability required by many product applications.   Crystal oscillators (usually quartz) can also be used as resonant components. Cut the crystal into two parallel crystal planes and deposit metal contacts on them. Quartz has piezoelectric effect, which means that when the crystal is placed under pressure, voltage will be generated on its crystal surface. On the contrary, when voltage is applied to the crystal, the crystal will also change its shape.