The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl Measurements >> Phase Noise and Jitter Measurements >> very close-in phase noise generation https://designers-guide.org/forum/YaBB.pl?num=1055988312 Message started by fast locker on Jun 18th, 2003, 7:05pm |
Title: very close-in phase noise generation Post by fast locker on Jun 18th, 2003, 7:05pm Hi, all, I've designed a frequency synthesizer with integrated VCO (around 2GHz). I got the following phase noise (PN) performance in the actual measurements (agilent 4352 vco pll tester). 1K -65dBc/Hz 10K -80dBc/Hz 100K -100dBc/Hz 600K -120dBc/Hz A clean crystal (fox 4106 44MHz) was used as the reference. The PLL type is integer. Phase detector update frequency is around 1MHz and the loop filter is off-chip (100KHz 3-dB bandwidth). The VDD's have been properly decoupled from GND with big caps. As shown in the list, the phase noise @ 10KHz and beyong is decent. However, the phase @1K and below is unaccepable. This affects the integrated phase error (RMS) a lot. As we know, usually the in-band PN curve is flat. However, I did see a flat curve, it is inceasing as frequency offset decrease from 1K to 100Hz. I am wondering what caused this kind of high very-close-in-band phase noise and if there is any way to reduce it. Any suggestions are appreciated. Thanks. |
Title: Re: very close-in phase noise generation Post by fast locker on Jun 21st, 2003, 11:15am OK. After a week's struggle with the close-in phase noise, I finally figured it out by myself. :) The problem of the close-in phase noise (1K and below) was caused by a lousy signal generator I used for reference of the 4352 VCO/PLL tester. When I switched to a better/newer siggen, Every problem was solved. I am now having a PN of -80~-90 @1K offset for in-band phase noise. fast locker |
The Designer's Guide Community Forum » Powered by YaBB 2.2.2! YaBB © 2000-2008. All Rights Reserved. |