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xinxin
Joined: 08 Oct 2003
Posts: 217
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 04 Dec 2003 1:56 How to measure GND noise on the PCB ? |
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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 ?
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brmadhukar
Joined: 21 Jun 2002
Posts: 844
Helped: 29
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| 04 Dec 2003 7:32 Re: How to measure GND noise on the PCB ? |
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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.
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tlp71@hotmail.com
Joined: 14 May 2002
Posts: 451
Helped: 3
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| 04 Dec 2003 8:22 Re: How to measure GND noise on the PCB ? |
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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.
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xinxin
Joined: 08 Oct 2003
Posts: 217
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| 04 Dec 2003 8:56 |
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| 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.
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