Tianqiong electronic technology has equipment research and development team, is committed to anti-vibration crystal oscillator independent innovation, research and development, production, sales, has a number of national patents, the main production and sales of crystal oscillator products include: thermostatic crystal oscillator, temperature-compensated crystal oscillator, general crystal oscillator, voltage-controlled crystal oscillator and so on. Today I will introduce the principle and characteristics of the above four kinds of anti-vibration crystals in detail.

(1)Constant Temperature Crystal Oscillator (hereinafter referred to as OCXO) 

The solution of this type of crystal oscillator for temperature stability adopts the thermostatic tank technology, where the crystal is placed in a thermostatic tank, and the tank is kept at a constant temperature by setting the thermostatic working point, which is not affected by the external temperature within a certain range and achieves the effect of stabilizing the output frequency. These crystals are mainly used in various types of communication equipments, including switches, SDH transmission equipments, mobile communication replay machines, GPS receivers, radio stations, digital TVs and military equipments. Depending on the user's needs, this type of crystal can be equipped with voltage control pins.

The main advantage of OCXO is that it has the best frequency and temperature characteristics among all types of crystals due to the thermostatic tank technology, and its short stability and phase noise are better due to the precise circuit design. The main disadvantages are high power consumption, large size, need about 5 minutes of heating time to work properly, etc.

(2)Temperature Compensated Crystal Oscillator (hereinafter referred to as TCXO)

The TCXO temperature compensated crystal oscillator is a quartz crystal oscillator that reduces the amount of change in oscillation frequency generated by changes in ambient temperature by means of an additional temperature compensation circuit. The principle of temperature compensation is to change the load capacitance in the oscillation circuit to compensate for the frequency drift of the resonator due to the ambient temperature change by changing the load capacitance with the temperature.

The function of the crystal is to provide the basic clock signal for the system. Often a system shares a single crystal, making it easier to keep all parts synchronized. Some communication systems use different crystals for the base frequency and the radio frequency and synchronize them by electronically adjusting the frequency.

The crystals are usually used in conjunction with phase-locked loop circuits to provide the clock frequency required by the system. If different subsystems require clock signals at different frequencies, they can be provided with different phase-locked loops connected to the same crystal.

Its solution for temperature stability uses some temperature compensation means, the main principle is to sense the ambient temperature and control the output frequency of the crystal after the temperature information is appropriately transformed to achieve the effect of stabilizing the output frequency. The traditional TCXO is to use analog devices for compensation, with the development of compensation technology, a lot of digital compensation of large TCXO began to appear, this digital compensation of the TCXO is also known as the DTCXO, with a single-chip computer for compensation, we call it the MCXO, due to the use of digital technology, this type of crystal again on the temperature characteristics of the temperature to achieve a high degree of accuracy, and can adapt to a wider range of operating temperature, mainly used in military applications. It is mainly used in military industry and harsh environment.

(3)Common Crystal Oscillator (SPXO)

This is a simple crystal oscillator, usually called a clock oscillator, and its working principle is to remove the "voltage control", "temperature compensation" and "AGC" part, which is completely done by the crystal's free oscillation. The operation principle is to remove the parts of "voltage control", "temperature compensation" and "AGC", and it is completely completed by the free oscillation of crystal. This type of crystal oscillator is mainly used in occasions where stability is not required.

(4) Voltage Controlled Crystal Oscillator (VCXO)

This is classified according to whether or not the crystal oscillator has a voltage control function. A type of crystal oscillator with a voltage control input pin is called VCXO, and the above three types of crystal oscillators can be equipped with voltage control ports.

Indicators of crystal oscillator

Total Frequency Difference: The maximum deviation of the crystal oscillator frequency from the given nominal frequency caused by all combinations of the specified operating and non-operating parameters within a specified time period.

Any crystal oscillator, frequency instability is absolute, the degree is different, a crystal oscillator output frequency over time to show the frequency instability of three factors: aging, drift and short stability.

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