De-jitterizer:
The second CDR is designed for a tighter transfer bandwidth and a larger high frequency tolerance, and is slave to the clock of the first.
Its larger tolerance is obtained widening the range of the phase comparator:

CDR2 tolerance at low frequencies is inferior to the one of CDR1, but is in general more than adequate;
CDR2 tolerance at high frequencies is not affected by the lateral eye opening (LEO) tolerance of CDR1, because CDR2 samples pulses that have already been regenerated ;
the range of the phase comparator (or of the shift register, whichever is smaller) becomes the limit to high frequency jitter tolerance in CDR2;
the phase comparator of PLL2 may either:
use divided frequencies at its inputs to achieve a wider range, or
use a normal comparator (± 0.5 U.I.) with the added information of the pointer, in accordance to P + 1/2 C, where P is the pointer cell index (integer, negative for less than half register, 0 in the centre cell, etc.) and where C is the comparator output, ranging from -1 to +1.
The characteristic cut-off frequency of CDR2 is lower than CDR1, and sets the overall regenerator bandwidth.
Own work
BORGATO Pierandrea