Clockmodul

Clockmodul (clock module) is a self-contained timing source that provides a stable reference frequency for digital circuits. It typically combines a frequency-determining element such as a quartz crystal or MEMS resonator with an oscillator circuit and an output buffer. Clock modules are used wherever precise and repeatable timing is required, and they can be stand-alone components on a board or integrated into larger modules or system-on-a-chip designs.

Common types include crystal-based oscillators, MEMS oscillators, and more precise variants such as OCXO and TCXO. Crystal oscillators use a fixed crystal resonant frequency; OCXOs are temperature-controlled with ovenized stabilization for very low drift; TCXOs provide temperature compensation with moderate drift. MEMS oscillators use microelectromechanical resonators and can offer small size and good shock resistance. Many clock modules provide multiple outputs and selectable frequencies, with output formats such as LVCMOS, LVPECL, LVDS, or CML, and supply voltages from 1.8 to 3.3 or 5 volts.

Key specifications include nominal frequency, frequency accuracy and stability over temperature, long-term aging, phase noise and jitter, output drive, and power supply rejection. Jitter is typically specified as peak-to-peak or rms over a given bandwidth. Stability is influenced by temperature range, load, and aging. Some modules offer holdover capabilities if the reference input is lost, useful in telecom and data networks.

Applications span computers, networking equipment, telecom infrastructure, test and measurement gear, and industrial control systems. Selection considerations include required frequency and stability, acceptable jitter, output format and drive, physical size, power requirements, and operating temperature. Interfacing often uses standard pins or programmable interfaces (SPI/I2C) to select frequency or configure features.

From a design perspective, clock modules must be integrated with careful power supply design, grounding, and PCB layout to minimize noise and skew. Reliability features such as temperature compensation, aging data, and calibration influence long-term performance.