On Fri, 07 May 2004 22:02:42 GMT, eatitcold wrote:

On Fri, 7 May 2004 07:55:14 +0100, "Alex Collins"
wrote:

Thanks to everyone who replied. I've now discovered the reason for the
disastrous noise on the Mini-Circuits VCO: Obviously I was using *extremely*
good RF PCB design techniques/layout, but these devices need even better
than the very best. They are abnormally sensitive - not so much to noise on
Vtune (20V tuning devices are less sensitive than the 5V wideband types) -
but to earthing - much more than normal - and much more than Mini-Circuits
own suggested PCB layout for the device suggests. And despite the fact that
the tiny metal can is mostly directly bonded earth pins. It's not feasible
how bad the results can be, even on a very good RF board! Apparently, the
quoted -75dBc phase noise figure is almost unattainable, except using
Mini-Circuits own metal block test jig.

A place I worked at years ago had nightmare probs with VCO phase
noise.
It depended on which freqs we were using though ( Z-Comm), some were
ok, others..yeesh!
Always had to have them in a can with soldered tops & undersides,
shielding everywhere, & filters , filters, filters :-)


newbies...

Improving VCO Phase Noise Performance Through Enhanced Characterization


http://www.highfrequencyelectronics....FE0104_Vye.pdf




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