[SI-LIST] Re: Question about Broadcom's PHY differential pairs termination
- From: "Dennis Han" <Dennis.Han@xxxxxxxxxxxxxxx>
- To: <weirsi@xxxxxxxxxx>, <jasonleehan@xxxxxxxxx>
- Date: Sun, 29 Jul 2007 13:40:22 -0700
... And I bet this transmitter is a current source, which is why the=0D=0A
resistor is needed, but the receiver still has to be terminated. =0D=0A
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From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]=0D=
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On Behalf Of steve weir=0D=0A
Sent: Sunday, July 29, 2007 10:03 PM=0D=0A
To: jasonleehan@xxxxxxxxx=0D=0A
Cc: SI LIST=0D=0A
Subject: [SI-LIST] Re: Question about Broadcom's PHY differential pairs=0D=
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termination=0D=0A
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Han, the driver is source terminated w/ the termination resistors. They=0D=
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need to be as close to the driver as possible.=0D=0A
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Steve.=0D=0A
Han Li wrote:=0D=0A
> Hi, experts,=0D=0A
> I'am designing with Broadcom PHY BCM5461s, I have a question =0D=0A
> about this phy's differential pairs termination.At Twisted pairs =0D=0A
> interface side(interface between PHY and Transformer),ASIC's Datasheet=0D=
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=0D=0A
> and Application note says "place differential pair termination =0D=0A
> resisters near PHY side as close as possible"=0D=0A
> It seems clear that we put differential paris termination neart =0D=
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> the end of receiver(Rx direction), this method is also recommended by =0D=
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> Dr. Howard Johnson in his book"High-Speed Digital Design-a handbook of=0D=
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black magic "=0D=0A
> pp-244,=0D=0A
> But why put termination also near driver side?(Tx direction) ,=0D=0A
> Could any one provide a deeper explanation? Thanks a lot!=0D=0A
> PS: A picture is inside illustrating a reference termination.=0D=0A
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> -- Binary/unsupported file stripped by Ecartis --=0D=0A
> -- Type: image/jpeg=0D=0A
> -- File: termination.JPG=0D=0A
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