[time-nuts] Low-Cost 6+ GHz Prescaler

[Samuel DEMEULEMEESTER]

About MMIC, that's true for the Minicircuits parts. Roll off is high at the
top of the range (from 13 dB to 8 dB), but the NBB-300 from RFMD seems to
have flat gain curve from DC to rated freq. This said, that's only paper and
I don't know the real behavior of this chip.

About sensitivity, 0 dBm is for 8 GHz, exceeding the rated specs of the
components (7 GHz for the ADF4107 for exemple). So, my "real" target is 6
GHz, but even at those freq, sensibility without amp stage is -10 dBm in the
worst case (it began to drop after 4 GHz). Doesn't looks sensitive enough,
does it ?


-----Message d'origine-----
De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
part de John Miles
Envoyé : vendredi 26 mars 2010 01:50
À : Discussion of precise time and frequency measurement
Objet : Re: [time-nuts] Low-Cost 6+ GHz Prescaler


> RFMD seems to produce some nice MMIC, for example the NBB-300
> (http://www.rfmd.com/CS/Documents/Nbb-300.pdf), but I never used a RFMD
> amplifier. I used Agilent/Avago MMIC since years with great results, but
> always with frequencies no more than 3 GHz.
>
> Anyone have some experience with DC-8/12 GHz MMIC and which's the best ?

My experience is that they roll off pretty quickly right where you are
looking for extra gain.  You'll probably end up with more gain where you
don't need/want it, and not as much as you'd like at the very top end of the
range.

The best off-the-shelf performance will probably come from Hittite's parts.
Compared to the Mini-Circuits parts, they are relatively power-hungry,
expensive, and hard to work with.  They're available only as LFCSP packages
or bare dice, and only in lots of 10 or more.

IMHO few users would reject your prescaler board due to a sensitivity spec
of 0 dBm.  At lower signal levels people are more likely to be using a
spectrum analyzer than a high-precision counter.

-- john, KE5FX


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