# Without In the continuous-time approximation, the average current

Without

the coarse-tuning loop, the locked time of the PLL would be longer due to the

smaller charge/discharge current of the fine-tuning loop. As illustrated in Fig

5 and Fig 6 the coarse-tuning loop is composedWithout

the coarse-tuning loop, the locked time of the PLL would be longer due to the

smaller charge/discharge current of the fine-tuning loop. As illustrated in Fig

5 and Fig 6 the coarse-tuning loop is composed of a coarse PFD and charge-pump

and the charge-pump has large charge/discharge current Ic. In the

continuous-time approximation,

the

average current Ich is given as

Ich =

Øe

Øe

is the phase difference between two input signals ext and int, and Ic

is the charge-pump current for the loop filter. The transfer function curve of

the coarse-tuning loop is shown in Fig. 8. The delay width |Ød| is the dead zone of the coarse PFD.

The operation of the coarse PFD can be divided into two cases. If the phase

difference Øe

> |Ød|, then the coarse charge-pump will

output the corresponding current Ic controlled by the coarse PFD. On the other

hand, if phase difference Øe < |Ød|, then the coarse charge-pump will
output no current. of a coarse PFD and charge-pump
and the charge-pump has large charge/discharge current Ic. In the
continuous-time approximation,
the
average current Ich is given as
Ich =
Øe
Øe
is the phase difference between two input signals ext and int, and Ic
is the charge-pump current for the loop filter. The transfer function curve of
the coarse-tuning loop is shown in Fig. 8. The delay width |Ød| is the dead zone of the coarse PFD.
The operation of the coarse PFD can be divided into two cases. If the phase
difference Øe
> |Ød|, then the coarse charge-pump will

output the corresponding current Ic controlled by the coarse PFD. On the other

hand, if phase difference Øe < |Ød|, then the coarse charge-pump will
output no current.