Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
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My Hobby Website:
Noise at resonance frequency - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: Noise at resonance frequency Posted: Mon Sep
26, 2005 11:27 am
I have build a VCO for a mixer IC. When i am viewing
the output power of VCO with Spectrum analyzer then there is a lot of
noise at and around desired resonance frequency. I am using a DC supply
of +- 5V and a regulated supply from 0V to 1.5V to check the response
of VCO resonance frequency. Noise is less when i am operating with 0V
or 1.5V regulated voltage, but if i give around 0.7V of regulated supply
then noise gets worse. I have also tried connecting capacitors with
my regulated supply but to no improvement. Can anybody please suggest
that how can i get rid of the noise ?
Post subject: VCO noisePosted: Wed Sep 28, 2005 3:13 pm
a bit confused. Do I understand that you are running the oscillator
proper from +/- 5V regulated, and that you're changing the control voltage
(from a different supply?) from 0 to 1.5V?
If your VCO uses a
varactor diode, you need to make sure that it's never forward biased.
That means avoiding the range of 0 to at least 0.7 V