ARRANGEMENT AND METHOD RELATING TO PHASE LOCKING COMPRISING STORING MEANS

摘要

The present invention relates to an arrangement for phase locking of a Voltage Controlled Oscillator (VCO) to a selected frequency harmonic among a number of predetermined or available frequencies (harmonics), comprising a reference generator for generating a reference frequency, a phase lock loop (1; 101; 10, 4, 5, 6, 9) for producing an output signal in response to the input reference frequency, said phase lock loop comprising (enclosing) a phase detector (1), a loop filter (10), said VCO (5), adding means (4) and a power splitter (6). The arrangement also includes a sweep generator (9). It further comprises or is associated with storing means 82) for storing information about, for each selectable or available frequency harmonic, a first (coarse) control voltage providing a VCO frequency output which is lower/higher than, and differs from the selected frequency (harmonic) by a given value (Δf1). That the sweep generator (9) adds (superimposes) a controllable sweep voltage to/on the first control voltage at least until a varying, second frequency difference (Δfc) between the output VCO frequency and the selected frequency harmonic reaches a given value. Monitoring/detecting means are provided for detecting the varying, second frequency difference (Δfc) between the selected frequency harmonic and the VCO output frequency, and sweep generator control means are provided for reducing the sweep rate until the VCO is phase locked to the selected frequency harmonic.