[SI-LIST] Decoupling of Oscillator
- From: Zhangkun <zhang_kun@xxxxxxxxxx>
- To: si-list <si-list@xxxxxxxxxxxxx>
- Date: Tue, 12 Nov 2002 14:43:49 +0800
Hi all
I meet one question about decoupling of oscillator. In our design, the power
supply of OSC is always isolated by one PI filter. In the side near OSC, there
are always one tantalum capacitor of 10uF and several ceramic capacitors of
0.1uF or 0.01uF. As we know the resonance frequency of tantalum capacitor is
about 3MHz. If the OSC is 50MHz, the spectrum will be speaded at 0, 50MHz,
100MHz, 150MHz, etc. There will be no power in the frequency range between 0
and 25MHz. Therefore, I think I could remove the tantalum capacitor. Is there
something wrong?
I think it will have nothing to do with the affection from OSC to outside
circuits. I am worrying about the affection from outside circuits to OSC. If
there is some noise of 2MHz and my OSC is of 50MHz, there will be modulation
between noise of 2MHz and clock signal of 50MHz. The output of OSC and the
clock signal will be affected by the noise of 2MHz. The bead will not isolate
the noise of 2MHz.
I want to know I could remove the 10uF tantalum capacitor or not. Why?
By the way, is there some people who do not use bead to isolate the power
supply of oscillator?
Best Regards
Zhangkun
2002.11.12
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
