Patent ID: 6023611
Filing Date: 2000-02-08
Classification: H03F,H03H

Abstract:
Filter device (3) intended for suppressing harmonics in radio frequency signals (S1,S2,S3,S4), comprising a first filter (3b) with fixed characteristic, and a second filter (3a,90,110), which is arranged in series with the first filter (3b), characterized in that the second filter (3a,90,110) is switchable and comprises at least one resonance circuit device (22,24,94,122,124) with a first and a second terminal, where the first terminal is connected to a transmission conducting element (25,96,125) included in the resonance circuit device, and the second terminal is connected to a reference potential (V.sub.REF), where the resonance circuit device (22,24,94,122,124) comprises:firstly, a first parallel connection of a first reactive element (L.sub.22,L.sub.24,L.sub.94,C.sub.122,C.sub.124) and at least one reversible PIN-diode (D.sub.22), andsecondly, a second reactive element (C.sub.21,C.sub.23,C.sub.93,L.sub.122,L.sub.124), where it is arranged in series with the first parallel connection, the second, switchable filter (3a,90,110) being arranged:to, in a first mode, provide good transmission of the radio frequency signal (S1,S3) in a first, lower, basic frequency band (51,81) and suppress at least one order of harmonics corresponding to this first basic frequency band (51,81), andto, in a second mode, provide good transmission of the radio frequency signal (S2,S4) in a second, higher, basic frequency band (61,91), the first filter (3b) suppressing at least one order of harmonics (62,92) corresponding to this second basic frequency band (61,91).