Crystal Oscillator is an electronic oscillator that uses piezoelectric effect. It generates electronic oscillation signals of precise frequency through the mechanical resonance of crystal (usually quartz crystal). Crystal oscillators are widely used in electronic circuits to provide stable clock signals, such as microprocessors, clock circuits and communication equipment.
Crystal oscillator generally refers to quartz crystal oscillator and quartz crystal resonator, which can also be directly called FJV3102RMTF Crystal oscillator. They are made by using the piezoelectric effect of quartz crystal.
The working principle of crystal oscillator is based on the piezoelectric effect of quartz crystal, which is a physical phenomenon that a specific material (such as quartz) generates an electric field under mechanical pressure. Conversely, when an electric field is applied to these materials, they will also produce mechanical deformation. When a crystal is cut into a proper shape and an alternating electric field is applied, it will oscillate at a specific frequency, which is called the resonant frequency of the crystal. It is very stable and is less affected by temperature, pressure and other environmental factors.
The crystal oscillator is usually enclosed in a metal or plastic housing and connected to a circuit board (PCB) through pins. The oscillation frequency provided by them can vary from several thousand Hz to one hundred megahertz, depending on the size, shape and other parameters of the crystal.
There are several types of crystal oscillator in design, such as simple quartz crystal, voltage controlled crystal oscillator (VCXO), temperature compensated crystal oscillator (TCXO), temperature controlled crystal oscillator (OCXO), etc. Different types of crystal oscillators are used in situations with different precision requirements.
The problem of placing crystal oscillator on the edge of PCB is mainly related to physical and electrical integrity. Here are some reasons why crystal oscillator should not be placed on the edge of PCB board:
1. Mechanical vulnerability: crystal oscillator is usually fragile, and it may be damaged by mechanical stress or accidental impact during PCB assembly and cutting when placed on the edge of PCB.
2. Electromagnetic interference (EMI): The high-frequency signal generated by the crystal oscillator may generate strong electromagnetic field, while the PCB edge is usually more vulnerable to external electromagnetic interference, which may affect the performance and stability of the crystal oscillator.
3. Signal integrity: placing the crystal oscillator on the edge of the PCB may lead to a longer signal path, increasing the delay and attenuation in the signal transmission process, thus affecting the quality of the clock signal.
4. Shielding: The crystal oscillator needs good shielding to protect it from external noise. Placing a crystal oscillator on the edge of a PCB may make shielding more difficult, because the edge may not provide enough ground area.
5. Manufacturing consideration: In the process of PCB manufacturing and assembly, the edge position may be limited, for example, the fixture used to fix the PCB may contact the edge part, thus affecting the installation of the crystal oscillator.
6. Thermal expansion: PCB will expand and contract under thermal change, and crystal oscillator placed on the edge may be damaged or change its resonance characteristics due to thermal stress.
To avoid these problems, the crystal oscillator should be placed in the PCB area that is relatively stable electrically and mechanically, as close as possible to the microprocessor or other devices that need a clock signal to reduce the signal path and delay. At the same time, enough grounding and shielding shall be ensured around the crystal oscillator to protect it from EMI and maintain signal integrity.
