In a PLL circuit, and a wireless mobile station with that PLL circuit, an LPF
charging constant current source, a discharging constant current source and a high-speed
charging constant current source are connected to an output terminal of a phase
comparator with current mode output. When a convergence frequency of the PLL circuit
is low, an input voltage of a VCO is increased from OV so as to be converged by
using the constant current source. However, when the convergence frequency of the
PLL circuit is high, the input voltage of the PLL circuit is temporarily increased
to the maximum voltage by using the constant current source. Thereafter, the input
voltage is gradually dropped from the maximum voltage so as to be converged by
using the constant current source.
