How to measure GND noise on the PCB ?

[xinxin]

How to measure GND noise on the PCB ?
I have a board of GSM phone. the performance of phase error is very bad . I want to check the cleanlily of GND , so meausre the noise on the GND with Spectrum analyzer , Ir is right ? any other problems to make the phase error bad ?

 

[brmadhukar]

How are you measuring the noise?
Are you connecting the probe and the GND reference both to the Board?

I suggest take a signal from "Earth== Chassis" and use it as ground reference. You may connect this to the ground of the board and then probe at the ground of the board. I am not so sure of this but I use it sometimes.


Phase noise:
Check the power supply pin. Filter it. This should solve 80% of your problems.

 

[tlp71@hotmail.com]

i think that if you would to use a spectrum analyzer you must to create a probe whit loop but you can find a radate emission.
if you have i think that is better to use an active probe.
Othervise you need to have a oscillope you must to have mathematical funztion as fft or power pectral density so you can find if spurious frequency are in ground plane.
Bye
G.

 

[xinxin]

The phase error is measured with CMU200 which simulating GSM Base . I think the bad phase error is related to the GND or Power Cleanity , so with spectrum analyzer , i want to find some noise spectrum added to the gnd or power.