What is Phase Noise? A Guide for RF and Timing Engineers

Phase noise describes the short-term, random fluctuations in the phase of a signal — in practical terms, how "pure" or "jittery" an oscillator's output frequency really is. Every real-world oscillator has some phase noise; the question is how much, and whether it's low enough for your application.

Why phase noise matters

An ideal oscillator would produce a perfectly clean sine wave at one exact frequency. Real oscillators instead produce a signal with tiny, rapid variations around that frequency — visible on a spectrum analyzer as "skirts" spreading out from the main signal. High phase noise can:

• Reduce receiver sensitivity in radio and radar systems
• Increase bit error rates in digital communications
• Degrade the accuracy of test and measurement equipment
• Cause reciprocal mixing that masks weak signals near strong ones

What drives phase noise?

Phase noise is influenced by the oscillator's design, the quality of the crystal itself, the electronics driving it, and how well it's isolated from vibration, temperature swings, and power supply noise. This is why OCXOs — with their stable internal temperature and typically more refined circuit design — generally achieve significantly lower phase noise than standard crystal oscillators or TCXOs.

Where low phase noise is critical

• RF and microwave communication systems
• Radar systems
• Satellite communications
• Test and measurement instrumentation
• High-resolution scientific instrumentation

Vikronix supplies low phase noise oscillators

Through our partnership with HCD Research, Vikronix supplies ultra-low phase noise OCXOs for applications where signal purity is critical. Browse our OCXO range or get in touch to discuss your phase noise requirements.