[time-nuts] fast freq. synthesis schemes

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Thu Oct 15 13:28:55 UTC 2009

On 10/14/09 6:08 PM, "John Miles" <jmiles at pop.net> wrote:

>> Ooohh.. Sampling Phase Detectors or Harmonic Mixers.. The problem
>> is that you have to hit them with a lot of power on the reference
>> port (+20dBm wouldn't be unusual)
>> Depending on your application,
>> making that much LO power that is suitably quiet is a challenge.
>> Presumably, though, you're not DC power limited, so that helps.
> Yes, if the goal is to breadboard something at home the constraints are
> looser in some ways and worse in others.  The Hittite parts are all QFNs
> that are annoying at best to dead-bug.
Ah.. But they come on eval boards with connectors<grin>.. (cost a bit more
too, as I recall

> The LO side isn't typically a problem in a sampler loop with a fixed drive
> frequency.  Mini-Circuits has a useful monolithic amplifier chip, the
> HELA-10, that yields 1 watt from HF to 1 GHz with a 3.5-dB NF.  You can feed
> it with a typical +15 dBm OCXO and put ~+25 dBm into your sampler for $20,
> and they even throw in the baluns.  Or for $75 they will sell you a
> gold-plated, connectorized and enclosed eval board.  One of the real
> unheralded bargains out there, as far as broadband driver amps are
> concerned.

That *is* handy to know..

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