Low jitter oscillators - special frequencies

From: Hal Murray (hmurray_at_suespammers.org)
Date: 02/06/05 

Date: Sun, 06 Feb 2005 17:53:46 -0600

Most special order crystal oscillator packages now have a
PLL in them. When you order a special frequency, they take
an unprogrammed unit off the shelf and program in the PLL
parameters. Delivery in a few days.

The problem is that you get the jitter specs of the PLL rather than
the crystal. The jitter turns out to be important for high speed A/D
applications. It's probably important in most RF work too.

Anybody know a good place to get real crystal oscillators made to order
in small volumes? I need 10 or 20 but the first try came up with
a min order of 250. I'm expecting 10-12 week delivery. I can live
with that.

Many crystal/oscillator companies used to be in the business
of making small runs to a specified frequency. How many are
left?

Anybody familiar with the details of the PLL setup? I assume
somebody did the math and figured out what frequencies they
have to stock in order to cover all the target frequencies they
might want to produce. How many different frequencies do they
have to stock? What sort of ratios are they using in the PLL?

When did everybody switch to PLLs? 

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