piclist 1998\11\15\111716a >
Thread: Philips TV/VCR PLL @ low Fosc anyone ?
picon face BY : Peter L. Peres email (remove spam text)

On Fri, 13 Nov 1998, Brian Robinson wrote:

> There are commercially available Fractional-N chips from Texas
> Instruments,   and I think that Philips has one now also.

I don't want fractional N, I'd rather build a straight programmable
divider with a bucketfull of HCTs.

> However, there are lots of potential problems with Fractional N to watch
> out for.  If I was building from scratch for HF, I would use a DDS chip,
>  probably  followed with some sort of simple PLL for very large frequency
> steps, and to clean up the DDS signal.  I believe one or two of the ham
> vendors have at least one radio with DDS.

Yes. Have you noticed the price tag ?

I was thinking of a cheap Philips tuner synth used with a much slower
clock (maybe 100 kHz) and a very slow loop to achieve a very fine channel
pitch. Usually they use 4MHz for a 200 kHz pitch so 100 kHz = 200/40 = 5
kHz which begins to be reasonable. I don't mind using a prescaler with
this setup.

The question was, whether any1 has tried to run the Philips parts this
slow, i.e. whether they are static CMOS, and whether there are nasty
implications on the I2C timing and on the phase comparator outputs (which
usually use some funky proprietary digital PLL algorythms near the lock
point for extra stability etc).



In reply to: <364CB8C3@cbmsmail.cb.lucent.com>
See also: www.piclist.com/techref/logic/dsps.htm?key=pll
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