high freq vco

patchell patchell at silcom.com
Sat Aug 12 16:08:20 CEST 2000

    I have lost track of this thread, so, maybe I am mis-speaking.  I don't
remember what the aplication for the high frequency VCO was......

    The first exponential VCO I did was based on the XR2207.  I quickly
discovered I could not tune the thing.  The problem turned out to be the 2207.
Maybe I just had a bad one, or maybe the problem is generic.  But even in the
data sheet I had the tuning linearity was something on the order of 1 or 2%, so
it may be that the 2207 is not suitable for a tunable pitch source, IMHO.

    I have never tested the VCO in the 4046.  I had never considered the 4046
partly because it is built with mosfets, which are not known for temperature
stability of any sort.  But, I could be wrong.

    I have used both parts to make PLL's.  They both work very well in that
application.  And I did use the 2207 as an LFO (works pretty nice that way).

danial stocks wrote:

> The 4046 pll chip has a vco that goes to 1MHz, HC4046 maybe even higher..
> dont worry abt the phase lock bit, just use the vco. makes a sq wave perfect
> for dividing. I think the XR2207 may go that high also but not sure..

    I have used the 2207 up at 1MHz, but that is about tops for this part.

> Cheers,
> Dan
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