PLL recommendations?

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I need a good PLL, and the frequency I need to generate is well beyond
the range of any 4046 type device. In particular, I have a need for
almost 80MHz. Any recommendations? I'm looking for inexpensive, small
parts count, and CMOS.

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Bill
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Re: PLL recommendations?

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Do you need an oscillator or a PLL?  If you just
need an oscillator, use one.  If you need a PLL
to lock to an external clock, you're going to have
to supply more information.




Re: PLL recommendations?
oN 21-Jan-04, Jim Stewart said:

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I need a PLL. I have a reference frequency, and need to generate another
frequency related to it. Except for the frequencies involved, it is
straightforward.

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Bill
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Re: PLL recommendations?

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frequency related to it. Except for the frequencies involved, it is
straightforward.

Ok, now we're getting somewhere.  What's the
exact input and output frequencies?  Any idea
as to phase noise requirements?  What's your
power and cost budgets?




Re: PLL recommendations?
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Of great importance is the type of application.
Do you need analog 80MHz with little phase noise, or digital
80MHz just as clock. What would be the input ?
Another XCO ?

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


Re: PLL recommendations?
oN 22-Jan-04, Rene Tschaggelar said:

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I have a clean reference frequency, and need to generate another which is at an
irrational relation to the first. It is desirable for the PLL output to be as
stable as possible. Loop response can be very slow, as the reference is stable,
and will not be switched. A secondary requirement, however, is that it may be
necessary to alter the generated frequency, depending on operating mode of the
system. This would still not require a rapid response, however.

The primary concern will be long-term stability of frequency.

--
Bill
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Re: PLL recommendations?
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 >which is at an irrational relation to the first. It is desirable
 >for the PLL output to be as stable as possible. Loop response
 >can be very slow, as the reference is stable, and will not
 >be switched. A secondary requirement, however, is that it may
 >be necessary to alter the generated frequency, depending on
 > operating mode of the system. This would still not require
 >a rapid response, however.
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You have the longterm stability of the source oscillator anyway.
If your source clock is as accurate as 1e-8, then your derived
clock will also be 1e-8, as a PLL does not add cycles.

The phase noise is a different matter altogether. There
the phase noise of the VCO is the one that matters.
You wouldn't want an external VCO, I guess.
Have a look at the Cypress CY27EE16 clock generator,
makes 200MHz.
For lower phase noise, requiring an external VCO,
the AD4001 from analog devices goes to 200MHz

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


Re: PLL recommendations?
oN 22-Jan-04, Rene Tschaggelar said:

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In this case, I can probably use one of the Cypress clocks, but I will =
have a look at the AD4001 anyway. Thanks!

--
Bill
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Re: PLL recommendations?

"William Meyer" ...
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at an irrational relation to the first.


If the ratio is irrational, what M/N are you going to program?

Regards,
Arie de Muynck



Re: PLL recommendations?
oN 24-Jan-04, Arie de Muynck said:

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You know, I thought about that later, and realized I must have been
thinking of something else at tht time. The ratio is, of course,
rational, albeit somewhat awkward.

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Bill
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Re: PLL recommendations?
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Take a look at this one: CY22393. It goes up to around 200MHz, programmable
and available from DigiKey for example.

--
Regards,
Andras Tantos
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Re: PLL recommendations?
oN 22-Jan-04, Andras Tantos said:

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Thanks! That looks like a good fit.

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Bill
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