Page 136 - Phase-Locked Loops Design, Simulation, and Applications

MIXED-SIGNAL PLL ANALYSIS Ronald E. Best 86

TABLE 3.2 Summary of Parameters of the Mixed-Signal PLL, Phase Detector Type 2
(EXOR)

phase detector, Table 3.3 summarizes the parameters of the Mixed-Signal PLL using phase
detector type 3, Table 3.4 summarizes the parameters of the mixed-signal PLL for phase
detector type 4a (PFD with voltage output). Table 3.5 summarizes the parameters of the
mixed-signal PLL using phase detector type 4b.

Optimizing the Lock Process

The lock time T is one of the most important parameters of a PLL. In most PLL applications,
L
we want the PLL to acquire lock fast—for example, within 20 μs. As shown in Eq. (3.62), the
lock time is inversely proportional to the natural frequency ω , and because the bandwidth of
n
the PLL [cf. the formula for ω in Eq. (3.21)] is proportional to natural frequency, fast lock
3db