Crystal oscillators are also divided into passive crystal oscillators[trade_no] and active crystal oscillators[trade_no]. The English name of passive crystal oscillator is different from that of active crystal oscillator. Passive crystal oscillator is crystal, while active crystal oscillator is called oscillator.
From the perspective of structural difference, the passive crystal oscillator[trade_no] is a non-polar element with two pins, which needs the help of a clock circuit to generate an oscillation signal, and it cannot oscillate by itself, so the term "passive crystal oscillator" is not accurate; The active crystal oscillator[trade_no] has four pins, which is a complete oscillator. In addition to quartz crystal, there are transistors and resistance capacitance components, so it is large in size.
Compared with ordinary crystal resonators[trade_no], active crystal resonators have higher technical requirements and more stable starting performance. They are generally used in high-end products. Each quartz crystal oscillator has different functions, but it also has excellent characteristics such as low power consumption, low voltage and current, low phase jitter, low phase noise and so on.
With the rapid development of electronic technology, oscillators[trade_no] are used more and more widely, but compared with the price of ordinary crystal oscillators, the price is often several times higher than that of ordinary crystal oscillators. Especially in the communication system circuit, the voltage controlled crystal oscillator (VCXO) is its key component, especially in the phase-locked loop circuit, clock recovery circuit and frequency synthesizer circuit, which can be said without exaggeration in the field of electronic communication technology.
Since its birth, active crystal oscillator has been playing an important role in the fields of communication, electronics, navigation, aerospace and medicine, and has a wide range of applications. In the early stage of the development of radio technology, it was used to generate high-frequency carrier voltage in the transmitter and as a local oscillator in the superheterodyne receiver, becoming the basic component of transmitting and receiving equipment.
