What is a crystal oscillator? What are its functions?

An OCXO (Oven-Controlled Crystal Oscillator) operates through a crystal that converts electrical energy into mechanical energy and vice versa, achieving stable, precise single-frequency oscillation. Under standard conditions, a typical OCXO offers an absolute frequency accuracy of 50 parts per million (ppm), with higher-grade models achieving even greater precision. Certain OCXOs can also be frequency-adjusted within a specific range by applying an external voltage, known as a voltage-controlled oscillator (VCXO).

The OCXO provides the system with a fundamental clock signal. Typically, a single OCXO is shared by the system to ensure synchronization across components. In some communication systems, the baseband and radio frequency operate on separate OCXOs, with synchronization achieved through electronic frequency adjustment.

OCXO is typically paired with a phase-locked loop (PLL) circuit to deliver the system's required clock frequency. When different subsystems require distinct clock frequencies, multiple PLLs connected to the same OCXO can be employed to meet these needs.

What are the functions of clocks and OCXO?

The function of OCXO is to provide a clock signal (a very stable frequency signal) to the microcontroller, ensuring that all internal components operate in sync and maintaining synchronization during communication with external devices.

Where is the OCXO in the motherboard, and what is its function?

Function of OCXO: The primary OCXO components on a motherboard are the real-time OCXO and clock OCXO. The real-time OCXO provides the oscillation frequency, which serves as the foundation for nearly all frequencies on the motherboard. If the OCXO is damaged, the motherboard will fail to operate properly. The OCXO, along with clock chips, sound card chips, network card chips, graphics cards, and other components, forms the oscillation circuit and is a critical source of clock signals across the entire board. To test the OCXO, measure the voltage across its two pins using a multimeter. Under normal conditions, the voltages will differ, creating a voltage differential. For waveform analysis, use an oscilloscope to measure both frequency and waveform. To measure resistance, connect the red probe to ground and the black probe to measure the resistance between the two pins.