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:
Jul. 16, 2002
Filed:
Nov. 22, 2000
Alfred Selz, Deisslingen, DE;
Thomson Licensing S.A., Boulogne, FR;
Abstract
The oscillator having a tunable resonant circuit has a switch for expanding the tuning range, which is connected in series with two coils jointly determining the oscillation frequency of the resonant circuit. A further coil, which is coupled to the resonant circuit in the region of the switch, is used to supply a switching voltage for the switch. In this arrangement, the other end of this third coil is coupled to a reference potential, with a capacitor, which acts as a short circuit for radio-frequency purposes, decoupling the switching voltage from the reference potential. Since the switching voltage is in this case coupled to an oscillator circuit node which is earthed for radio-frequency purposes, it is of no significance in this case which resistor is used to couple the switching voltage. This means that the resonant circuit is not resistively damped by the connection of the switching voltage. Coupled to the other end of the switching diode is a further component, preferably a fourth coil, which has the same inductance as the third coil, in order to dissipate the switching voltage. The first two coils are advantageously of the same size, so that this circuit coil jointly determining the oscillation frequency is earthed by the third coil exactly at its center. This means that the quality factor and the oscillation properties of the resonant circuit are not adversely affected.