phase noise measurement

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J0hn

Joined: 08 Feb 2006
Posts: 43
Helped: 2

20 Jun 2006 14:46 phase noise measurement

Hi, i couldn't find any topic related to phase noise measurement. I suppose to do some phase noise measurement, but could someone please tell me what is exactly phase noise? How did it come about? Or is that any link that i can refer to enhance my understanding? Thanks.

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DDavid

Joined: 06 Apr 2006
Posts: 232
Helped: 22

20 Jun 2006 14:56 Re: phase noise measurement

Hi,

I think that next paper will answer to you question.

David

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Soben

Joined: 19 Oct 2005
Posts: 105
Helped: 24

20 Jun 2006 18:12 Re: phase noise measurement

J0hn wrote:

Hi, i couldn't find any topic related to phase noise measurement. I suppose to do some phase noise measurement.

There are different ways to measure phase noise, but depents how low noise is the signal u want to measure. An easy one is using a spectrum analyser though needs the internall referense oscillator of the spectrum analyser to have much less phase noise than the signal you measure. Or If you have a Phase noise Gear like the Agilent E5505 (u can look at their webpage has also information about phase noise).

Quote:

but could someone please tell me what is exactly phase noise? How did it come about? Or is that any link that i can refer to enhance my understanding? Thanks.

Phase noise is a figure of merit to describe short term stability of an oscillator. All oscillators have a frequency drifting that is a result of Amplitude Modulation and Phase Modulation of your Carrier signal with low frequency 1/f noise (flicker Noise)from the nonlinear characteristics of your amplifier inside the oscillator loop.That results to a signal with side bands that spread to few KHz offsets from your Carrier. Phase Noise L(f) is specified as noise Power, relative to carrier Power, in one Hz bandwidth at a given offset and is the result only of Phase modulation.AM modulation noise is much less than PM and not the dominant source of noise in Oscillators.

Look at the picture to get what i mean with that description.

Also you can have a look at wenzel website they have some nice articles about phase noise.

http://www.wenzel.com/documents/circuits.html

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