Siemens-albis, Ag

Bruno Fognini

Helmut Heinz

A frequency synthesizing device comprises two reference frequency generators RG1 and RG2, an offset stage OS and a phase-locked loop PLL. In the phase-locked loop, which operates as a tracking filter, the output frequency fs.sub.A is generated by the addition of the frequencies f.sub.RG1 and f.sub.OS. The output frequency fs.sub.A has a very high spectral purity, since all interfering spurious signals are blocked by the tracking filter. By a proper selection of the reference frequencies f.sub.RG1, f.sub.RG2 and f.sub.OR, it is ensured that all interfering spurious signals lie outside the bandwidth B.sub.TF of the tracking filter and are accordingly blocked. As a result, it is not necessary to filter the signals S.sub.RG1, S.sub.RG2 and S.sub.OS.

Frequency synthesizing device

The controlled switching array comprises four commutator components and four associated signal distributors. Each signal distributor has an input side to which an input signal is applied which, in turn, is fed to a respective input on the input sides of the commutator components. The commutator components are symmetrically arranged on both sides of a printed circuit board. There thus results a favorable decoupling of signal lines from each other as well as from the output side.

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Zurich, Switzerland

Bruno Fognini