Patent ID: 6215361
Filing Date: 2001-04-10
Classification: H03L,H04N,Y10S

Abstract:
A phase-locked loop including a comparator, a charge pump, a capacitive filter, a voltage-controlled oscillator and a phase adjustment device, the comparator comparing the phases of an input pulse signal and of a reference pulse signal supplied by the phase adjustment device, and generating charge and discharge control signals, the charge pump being capable of charging or discharging the capacitive filter according to the charge and discharge control signals, the filter being charged or discharged when these signals are in a first state and insulated from the charge pump when they are in a second state, including a device for limiting the charge and discharge current of the capacitive filter, this device including windowing circuits for limiting a first time period during which the charge and discharge control signals are in the first state, wherein the limiting device includes a circuit for detecting the locking of the loop and wherein the charge pump includes means for limiting the value of the charge or discharge current of the filter, the circuit for detecting the locking generating a locking detection signal representative of the fact that the loop is or is not locked, the detection signal being supplied to the windowing circuits and to the charge pump, to limit the first time period during which the charge and discharge control signals are in their first state to less than a second time period during which the loop is locked, and to limit the value of the charge or discharge current when the loop is not locked.