EMRFD Message Archive 2027

Message Date From Subject
2027 2008-09-07 21:43:05 David Brainerd DBM driven by PECL
Has anyone driven a DBM with the output of a PECL flip-flop? Looks
like it might be just about the right level for a +7dbm DBM.

Dave - WB6DHW
<http://wb6dhw.com>
2028 2008-09-07 21:58:55 brainerd@wildblue... Re: DBM driven by PECL
That should read LVPECL flip-flop.

On 8 Sep 2008 at 4:43, David Brainerd wrote:

> Has anyone driven a DBM with the output of a PECL flip-flop? Looks
> like it might be just about the right level for a +7dbm DBM.
>
Dave - WB6DHW
<http://wb6dhw.com>
2033 2008-09-08 13:21:41 Gary Johnson Re: DBM driven by PECL
LVPECL (or PECL) provide an output swing of 700-800 mV p-p into 50 ohms, on each of
their complementary outputs. That works out to 2.0 dBm. You could use a conventional
1:1 xfmr to roughly double the power output by taking advantage of the differential
outputs. But Zout for PECL is about 3 or 4 ohms, so in any case this would certainly not
look like a 50 ohm source. That alone makes it undesirable as a DBM driver unless you
back-terminate it and give up half the output power.

Note that you also need to dc terminate each PECL output to about Vcc-2 V. That could be
provided thru a center-tap on the xfmr primary.

Nice app notes