As we all know, crystal oscillator is known as the "heart" of electronic products. It is one of the electronic components that provide the most accurate frequency selection, frequency stabilization and clock functions. It is used in the Internet of Things, smart wear, smart medical, security, automotive electronics and other applications. It can be seen everywhere, and its market scale continues to expand, so the growth and demand for crystal oscillators have always been on an upward slope. With the current demand for high fundamental frequency applications such as 5G communications and Wi-Fi6, which are relatively popular, the demand for quartz crystal oscillators has increased rapidly. According to the current industry public opinion trends, 5G construction and consumption popularization will be further accelerated. The forecast data of 5G network equipment, fixed wireless services and 5G mobile phones by analysts shows that network equipment with a low compound annual growth rate will still reach 59.3 between 2020 and 2025. %, in the near future, there may be a situation where crystal oscillators are hard to find on the market

Crystal oscillator is a high-precision and high-stability oscillator. It is widely used in various types of oscillation circuits such as color TVs, computers, remote controls, and communication systems for frequency generators and clock signals for data processing equipment. And provide a reference signal for a specific system. 　　Quartz crystal oscillator is a kind of resonant device made by using the piezoelectric effect of quartz crystal (crystal of silicon dioxide). Its basic structure is roughly as follows: a slice (referred to as a wafer for short) is cut from a piece of quartz crystal at a certain azimuth angle. It can be square, rectangular or round, etc.), silver layers are coated on its two corresponding surfaces as electrodes, each electrode is welded with a lead wire to the pin, and a package shell is added. Quartz crystal resonator, referred to as quartz crystal or crystal, crystal oscillator for short. Its products are generally packaged in metal shells, but also in glass, ceramic or plastic packages

Aging refers to the change in the frequency of the crystal. It can change in both positive and negative directions. The aging process is caused by the change in the frequency of the oscillator used by the crystal.Aging will be mainly affected by two factors, namely pollution and pressure. Experiments have shown that contamination of crystal wafers will bring about negative changes, while excessive pressure will usually bring about positive changes. 　　When the crystal chip is mounted on the chassis, it is likely to be squeezed or twisted due to the support structure, which will bring pressure to the crystal chip, which will release or relax over time, leading to a positive frequency shift. When assembling the crystal, the proper equipment method and proper chassis help to reduce and reduce unnecessary stress. The installed crystal can be heat treated to accelerate the movement and alleviation of this pressure

We must first understand its operating frequency and adjust the frequency difference under the specified conditions, the reference temperature (25 ± 2 ℃) of the allowable deviation of the operating frequency from the nominal frequency, for a high-reliability system design, the quartz crystal oscillator The choice is very important, especially the design of a system with wake-up from sleep. If the selection is incorrect, it is easy to cause the crystal oscillator to start to oscillate very slowly or not at all. Perhaps it is because the excitation power of the supply voltage to the quartz crystal is reduced. This phenomenon is not particularly obvious at power-on reset, because the circuit is powered on. With enough disturbance, it is easy to establish oscillations. In the wake of sleep, the disturbance of the circuit is much smaller than when the power is turned on, and it becomes a little difficult to start the vibration. In the oscillation circuit, the quartz crystal can neither be over-excited nor under-excited. The choice of crystal must at least consider: nominal frequency, resonance frequency, load capacitance, excitation power, temperature characteristics, and long-term stability

Choose the standard quartz crystal from a manufacturer with proven quality, high reliability, promising development, and good reputation through practice. Obsolete or inferior quartz crystals cannot be used.The technical functions, quality levels, and operating conditions of the quartz crystal oscillator should meet the requirements of the planning circuit.In the case of satisfactory functional parameters, a quartz crystal with low power consumption, low thermal resistance, low loss angle, high power gain, and high efficiency should be selected.The best choice of domestic quartz crystal oscillator. The first choice is the quartz crystal that has passed the certification and conforms to the national standard; the quartz crystal that can be supplied stably through the test and meets the requirements; Youcheng advises to use other quartz crystals that meet the requirements