Some time ago I found this on the www:
Atmel, Digital Frequency/Phase Comparator (DFPC):
Is this DFPC (using 4000 or 74HC series logic) better that the phase comparators used in e.g. 4046, 74HC7046, 74HC9046?
4046 schematic on page 5:When was the DFPC invented? Is it free to the DFPC for any purpose?
Glenn