An oscillator supplies a repeating timing signal, but its nominal frequency is only one part of the specification. Product performance also depends on frequency stability, jitter, output compatibility, power and how the clock is integrated into the board. Begin with the receiving device's clock requirements before selecting a part.
Frequency accuracy and stability are different from jitter
Frequency stability describes variation relative to the nominal frequency, commonly expressed in parts per million (ppm). Check which effects the specification includes, such as temperature, initial tolerance, aging, supply or load variation. Jitter describes short-term timing variation. Compare jitter values only when the measurement definition and, where applicable, integration range match.
For a simple frequency example, a 25 MHz clock with a 20 ppm deviation differs from its nominal frequency by 500 Hz. This arithmetic does not describe its jitter or prove that the clock meets a particular interface requirement.
Match the electrical interface
Check the clock input requirements of the processor, converter, radio or other receiving device. Confirm output format, supply voltage, load, termination, rise and fall times and any enable or standby behavior. A matching package and frequency do not establish interchangeability.
Build a comparison sheet before requesting quotations
| Field | Information to record |
|---|---|
| Frequency | Required nominal value, tolerance and any programming requirements. |
| Stability | Limit and included conditions, with operating temperature and aging assumptions. |
| Timing noise | Required jitter or phase-noise metric and the measurement conditions used by the system specification. |
| Electrical compatibility | Output type, supply range, load, termination and control-pin behavior. |
| Power | Operating and standby current under the intended conditions. |
| Mechanical fit | Package, pin assignment, footprint and assembly requirements. |
SiTime's overview of fundamental oscillator parameters explains these specifications and highlights additional factors such as startup time. Treat it as a guide to reading specifications; use the current datasheet for the exact part being purchased.
Choose a technology from the application requirements
Crystal, MEMS, programmable and compensated oscillator products offer different combinations of performance and features. Compare complete part specifications rather than assuming one technology is always smaller, lower power or more accurate. A premium device only adds value when its capabilities address a requirement in the product.
Verify performance on the assembled board
- Review the clock path: Confirm pinout, routing, termination and the receiving device's requirements.
- Check power integrity: Apply the manufacturer's decoupling guidance and evaluate supply noise under real operating loads.
- Test environmental behavior: Measure operation across the intended temperature and supply range.
- Test startup and control states: Verify startup, enable, standby and restart behavior in the system.
- Record acceptance criteria: Define the measurements an alternative part must pass before approval.
Keep the qualification results with the BOM. Procurement should confirm the complete ordering code, programmed frequency where applicable, temperature grade and delivery terms. This makes a supplier comparison more useful than comparing unit prices alone.
For further preparation, see our component datasheet review guide or send a sourcing enquiry with your approved part requirements.
