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Phase noise measurement

I wrote my diploma thesis about phase noise measurement near the carrier. Even more than a decade later the topic is still actual and critical, because phase noise influences the accuracy of our communication systems. It makes a difference in how good your smartphone works in the high frequency range e.g. Wi-Fi and cellular communication. This gets even more important when applied in critical system devices.

The diploma thesis was written in German, but with frequent requests in the past years, I decided to re-publish on my new site. Please feel free to reference, but do not place copies on websites.

The phase noise of voltage-controlled quartz oscillators is created by its fluctuations in the phase and causes a spreading of the spectrum.
The basics of noise, oscillators, PLL, and four-diode ring mixers as phase detectors are explained in this diploma thesis.

measuring station

All of the following concepts of measuring phase noise have been evaluated:

  • simplest method: measurement with the spectrum analyzer.
  • frequency discriminator method
  • frequency discriminator method with cross-correlation
  • phase detector method
  • phase detector method with cross-correlation
  • phase detector method with PLL (phase locked loop)
  • phase detector method with cross-correlation and PLL and one reference oscillator
  • phase detector method with cross-correlation and PLL and two reference oscillators

The conclusion of this diploma thesis is, that phase noise measurements are possible from 3 Hz down to a noise floor of -132 dBm, based on available components in 2008.

Download the publication file:


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