The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 28, 1991
Filed:
Oct. 18, 1989
Bruno Fognini, Zurich, CH;
Helmut Heinz, Munich, DE;
Siemens-Albis Aktiengesellschaft, Zurich, CH;
Abstract
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.