The jitter tolerance of the second CDR in a de-jitterizer is influenced by the values of characteristic frequency and damping coefficient, whatever the loop order and type. If the loop is a second order of the first type, the actual shape of the tolerance function depends markedly on the damping coefficient. If the tolerance of this second CDR is approximated by an asymptotic model, it is prudent to use omega_cut-off instead of omega_n to define the two asymptotes.