[SI-LIST] Re: Decoupling of Oscillator
- From: "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx>
- To: "'MikonCons@xxxxxxx'" <MikonCons@xxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Mon, 25 Nov 2002 16:04:01 -0700
Hi Mike,
While I agree with your comments I am still
left wondering what one does when the clock
is NOT the only source of a coherent signal.
That is to say; When multiple chips source a
clock. Should a ferrite be added on ALL Vcc pins??
This could be very crowded when the source is a
BGA.
Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel: 303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Email: charles.grasso@xxxxxxxxxxxx;
Email Alternate: chasgrasso@xxxxxxxx
-----Original Message-----
From: MikonCons@xxxxxxx [mailto:MikonCons@xxxxxxx]
Sent: Monday, November 25, 2002 3:28 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Decoupling of Oscillator
In a message dated 11/24/2002 7:44:59 PM Pacific Standard Time,
bdewitt@xxxxxxxxxxxxx writes:
> Maybe someone can explain it, but I've never understood adding _any_
> additional impedance to a reference plane (call it "ground") connection.
> It
> seems I should always be aiming for the common impedance here for
reference
> purposes. Creating an isolated power to reference current loop does seem
> to
> show advantage when both high speed digital and low level analog live on
> the
> same board. Am I missing something?
Right on target, Brent. Decoupled moats with power input PI-filters and
ground "bridges" (under the outputs) to the islands created are an effective
noise isolation mechanism for clocks, but increasing the impedance on the
ground connection (in my experience) has always increased the SI and EMC
problems. On the contrary, I have successfully reduced radiated emisions,
reduced jitter performance, and cleaned up other SI problems on over 200
PCBs for ~80 different clients over the past decade by using continuous
ground planes (along with several other of my tricks of the trade).
Mike
Michael L. Conn
Owner/Principal Consultant
Mikon Consulting
Cell: (408)821-9843
*** Serving Your Needs with Technical Excellence ***
------------------------------------------------------------------
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
------------------------------------------------------------------
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:
