Patent ID: 6661293
Filing Date: 2003-12-09
Classification: H03L

Abstract:
A method for setting a frequency in a phase locked loop having, in that order, a reference divider to decrease a reference frequency, phase difference detector, a charge pump, a filter, a voltage-controlled oscillator, and a programmable VCO-divider to decrease the frequency produced by the voltage-controlled oscillator, which method comprises the steps of:comparing phases of the signals output by the reference divider and VCO-divider, processing signals produced by said comparison and controlling said oscillator with a control voltage produced by the processing mentioned above, and resetting the reference divider and VCO-divider after a new frequency setting has been made in the programmable VCO-divider, wherein after the new frequency setting has been made, the following actions are taken at least during a first cycle of the reference divider: forming a pulse, a length of which is proportional to a difference between the new frequency setting and an actual frequency output by the voltage controlled oscillator, and changing the control voltage of the voltage-controlled oscillator proportionally to the length of said pulse, by an amount corresponding substantially to said frequency difference.