The naming methods of each manufacturer are different. The products are widely used in military and civilian communication equipment, GPS positioning systems, timing systems, digital TVs, wireless base stations, repeaters, private networks, and monitoring and transmission equipment. , measurement and control measurement, railway signaling, medical equipment, instrumentation, industrial automation control, aerospace, shipboard communications, radio, precision guidance, radar and other fields. It can be divided into 4 major categories according to different application fields. 1) Ordinary crystal oscillator (Packaged crystal Oscillator)
It is a crystal oscillator without temperature control or temperature compensation device, and the frequency and temperature characteristics are basically determined by the crystal components used, referred to as "ordinary crystal oscillator" (PXO)". PXO is the most basic and simplest crystal oscillator. It is a frequency device that integrates crystal components and oscillation circuits on a circuit board according to design requirements and is packaged in a shell. 1: PXO using the same metal package as the semiconductor device DIP (DIP14 or DIP8-pin IC compatible package) structural standard. 2: 3.2×2.5, 5.0×3.2, 7.0×5. (mm) using SMD package.
2) Voltage Controlled Crystal Oscillator
It is a crystal oscillator that uses an external control voltage to shift or modulate the frequency according to a certain rule, referred to as " Voltage Controlled Crystal Oscillator (VCXO)”. VCXO is mainly composed of crystal components, varactor diodes and oscillator circuits. Its working principle is to change the capacitance of the varactor diode by controlling the voltage, thereby "pulling" the frequency of the crystal component to achieve frequency deviation or modulation.
3) Temperature Compensated Crystal Oscillator
It is a crystal that uses a compensation system within the oscillator to reduce frequency changes caused by ambient temperature. Oscillator, referred to as "temperature compensated crystal oscillator (TCXO)". After the TCXO is powered on at room temperature, it can generally establish a stable frequency state within tens of milliseconds. When the ambient temperature changes normally, the TCXO will quickly rebuild and stabilize. This is its main beneficial application.
4) Oven Controlled Crystal Oscillator
It is a crystal oscillator that maintains frequency stability through internal constant temperature, referred to as "Oven Controlled Crystal Oscillator (OCXO)" ".
OCXO is mainly composed of crystal components, temperature control circuits and oscillation circuits. Its working principle is to use a specially designed heating temperature control circuit and structure to combine the crystal components and (in a double-layer constant temperature design) oscillation circuit The constant temperature is in a small special temperature range so that its oscillation frequency is not affected by changes in external ambient temperature to achieve high stability.
The operating frequency is generally within 200MHz, and can also be reached to several or even dozens of GHz through phase-locked frequency multiplication and other solutions.