Re: [SI-LIST] : PECL oscillator termination

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From: Tae-Kwang Jeon (tkjeon@vps6.lsil.com)
Date: Thu Nov 09 2000 - 18:32:28 PST


Hi Mike,

>>
>> #3 In the case of #2, the resistors are supposed to be grounded, then what
>> if I make them in series?
>>
>
>In series with what? WIth the praces of the diffpair?
>The resistors are there to provide bias. Make them in series with the pair -
and
>you divide your signal between your resistor and the trx-line. The series
>termination does just that, but then, if you need AC-coupling, wher's your
bias?
>YOu will open can of worms, when everything is simple - connect 330 Ohm to GND,
>run your traces, put the caps in series (where you like; some people have
>different preferences - beginning, end) and terminate - either for diff. mode
>(diff. impedance resistor between traces in the end) of for common mode (one
>trace impedance resistor to GND from each trace in the end).
>
>Mike.
>

Yes, I agree with you on the DC-biasing resistor.
The reason for asking #3 is that I read an article the other day from Web -
I don't remember what the site was right now - saying resistor connection in
series with the cap could improve the PECL termination. So I was wondering
if it really works because I'm working on PECL-to-PECL interface for my
system.

Regards,
TK
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TaeKwang Jeon, LSI Logic Corp.
1525 McCarthy Blvd Phone: (408) 433-6818
MS G-715 Fax : (408) 433-2840
Milpitas, CA 95035 Email: tkjeon@lsil.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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