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Measurements >> Phase Noise and Jitter Measurements >> Measuring Free Run LC VCO's Phase Noise
https://designers-guide.org/forum/YaBB.pl?num=1204457051

Message started by neoflash on Mar 2^nd, 2008, 3:24am

Title: Measuring Free Run LC VCO's Phase Noise
Post by neoflash on Mar 2^nd, 2008, 3:24am

It seems difficult to measure free running LC-VCO's phase noise with E5052-A.

During measuring, it shows quick variation in low frequency band. Any experience with it?

Title: Re: Measuring Free Run LC VCO's Phase Noise
Post by ritchie_ch on Apr 30^th, 2008, 8:43pm

If the measured VCO is biased from a regulator or something except a pin from the out-chip supply, it may encountered the problem you have mentioned. Based on my experience, there are 2 methods you can try:
1. tuning the IF gain of E5052 to a lower value;
2. using the 'supply voltage' of the E5052 to bias the VCO and adding a huge capacitor at the supply node if necessary.

Title: Re: Measuring Free Run LC VCO's Phase Noise
Post by Miconos on Jun 29^th, 2008, 12:17am

Give more details:
is it on Silicon?
how do you regulate and bias your VCO?
do you have a VCO buffer?