Importance

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Abstract

A variable frequency signal generator includes a phase locked loop having a variable frequency oscillator which has a control port to which a frequency determining signal is applied, the output of the oscillator being fed via a frequency divider to a phase sensitive detector where it is compared with a reference frequency signal, the result of said comparison being arranged to generate a comparison signal which is fed to a loop filter which is coupled to said control port; and the signal generator having a frequency control signal applied thereto and comprising a first path being arranged to adjust the division ratio of the frequency divider, and a second path including a combiner for combining said frequency control signal and said comparison signal to produce said frequency determining signal; and a calibrator for adjusting the relative characteristics of said first and second paths to compensate for effects arising from tuning sensitivity dependence on frequency of said variable frequency generator.

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First Claim