Baa. Antao et al., BEHAVIORAL MODELING PHASE-LOCKED LOOPS FOR MIXED-MODE SIMULATION, Analog integrated circuits and signal processing, 10(1-2), 1996, pp. 45-65
Phase-locked Loops(PLLs) are a class of feedback systems with wide ran
ge of applications. A PLL in its entirety can be viewed as a closed-lo
op servosystem, comprised of three major functional subsystems; 1) Pha
se detectors, 2) Loop filters and 3) Voltage/Current controlled oscill
ators. The overall characteristics of the phase-locked loop are depend
ent on the realization of individual subsystems which have mixed analo
g-digital implementations. In simulating a PLL, one has to deal with t
he mixed-signal nature of most implementations, as well as the problem
of simulating the PLL over a large number of signal cycles. Long simu
lation run times plague the simulation of a PLL using a conventional s
imulator, sometimes making such simulation impractical. In the methodo
logy described in this paper, these drawbacks are overcome by the use
of behavioral models and a mixed-signal simulation platform. This pape
r presents a general mixed-mode behavioral simulation methodology and
the derivation of behavioral simulation models for various kinds of PL
Ls. The top-down and bottom-up modeling paradigms are illustrated thro
ugh the use of examples of actual PLL designs. The simulation models a
re generated for the AT&T Bell Laboratories mixed analog-digital simul
ator, ATTSIM.