What is an active crystal oscillator? | Analysis of the performance advantages of active crystal oscillators

We often compare the crystal oscillator to the heart of the digital circuit. This is because all the work of the digital circuit is inseparable from the clock signal. The crystal oscillator directly controls the entire system. If the crystal oscillator does not work, the entire system will be paralyzed. Therefore, the crystal oscillator is a prerequisite for the digital circuit to start working.

The crystal oscillator we often talk about is a quartz crystal oscillator and a quartz crystal resonator. They are all made using the piezoelectric effect of quartz crystals. Applying an electric field to the two electrodes of a quartz crystal will cause the crystal to deform mechanically. Conversely, if mechanical pressure is applied to both sides of the crystal, an electric field will be generated on the crystal. Moreover, these two phenomena are reversible. Using this characteristic, applying an alternating voltage on both sides of the crystal will cause the chip to vibrate mechanically and generate an alternating electric field at the same time. This vibration and electric field are generally very small, but at a certain frequency, the amplitude will increase significantly. This is piezoelectric resonance, similar to the LC loop resonance we often see.

As the heart of the digital circuit, how does the crystal oscillator work in smart products? Smart home products such as air conditioners, curtains, security, and monitoring all require wireless transmission modules. They use protocols such as Bluetooth, WIFI, or ZIGBEE to send the module from one end to the other, or directly control it through a mobile phone. The crystal oscillator is the core component in the wireless module and affects the stability of the entire system. Therefore, choosing the crystal oscillator used in the system determines the success or failure of the digital circuit.

Due to the importance of crystal oscillators in digital circuits, we need to be careful when using and designing:

1. There is a quartz crystal inside the crystal oscillator. When it is hit or dropped, it is easy to cause the quartz crystal to break and break, which will cause the crystal oscillator to fail to oscillate. Therefore, when designing the circuit, you must consider the reliable installation of the crystal oscillator, and try not to place it close to the edge of the board, the device housing, etc.

2. When welding manually or by machine, pay attention to the welding temperature. The crystal oscillator is sensitive to temperature. The temperature should not be too high during welding, and the heating time should be as short as possible.