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Old July 5th 14, 08:32 AM posted to rec.radio.amateur.homebrew
Rob[_8_] Rob[_8_] is offline
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First recorded activity by RadioBanter: Dec 2008
Posts: 375
Default MC145151 PLL... anybody made anything with it?

Eric Weaver wrote:
So pardon my ignorance, what's the hip PLL or at least
counter/phase-detector these days?


Hip these days is not to use a PLL but use an NCO.
Of course there are differences in the spurious and noise output.

However, when still using a PLL and using it for amateur purposes
(small steps relative to the frequency), at least go for a dual-modulus
system. Else the phase comparator has to operate at the frequency of
the channel step, or even at a fraction of that when a fixed prescaler
is required in front of the programmable divider. As the MC145151
at best operates up to 25 MHz, you often will require a prescaler.
A low phase comparator frequency means a slow loop.

The MC145152 is a dual-modulus version. However, note that with a
dual-modulus system it is more complicated to generate the setting
information, probably requiring a microcontroller. Once you are going
to need that, it is easier to use a more modern IC programmed using I2C.