Frequency synthesizers, like Analog's ADF411x often have prescalers in their PLL which divide by 16/17, 32/33 or 64/65? What's the 2^N+1 value used for?
Asked
Active
Viewed 1,063 times
2 Answers
7
A dual-modulus (fractional N) pre-scaler gives the PLL increased resolution, without compromising things like lock time and noise. See this app note.
Leon Heller
- 38,774
- 2
- 60
- 96
-
That's a pretty good read for the fractional N system. I didn't know that's how it worked. Thanks! – W5VO Dec 18 '10 at 17:42
-
Note that the use of a dual-modulus prescaler does not, by itself, imply a fractional-N design. N/N+1 dividers are also used in integer-N parts, like most of the ADF411x series. – user572 Jul 06 '12 at 05:30
2
Another Excellent PLL reference is this one
