Transmitter filter arrangement for multiband mobile phone
AssigneeNokia Corporation
InventorJuha Ellä
Life of this patent
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Abstract
A filter arrangement for use in a multiband dual-mode mobile phone. In particular, the mobile phone is operable in a W-CDMA mode and a band-reject filter comprising at least a series and a shunt acoustic-wave resonators is used to create a deep notch at the receive frequency band. The band-reject filter further includes a plurality of inductive elements for matching static capacitance of the resonators at the passband frequency. The mobile phone is also operable in 1800 and 1900 GSM bands. The band-reject filter is operatively connected to a harmonic trap in order to eliminate the third harmonic of these GSM bands. The mobile phone is also operable in the lower GSM band, for which a harmonic filter can share an antenna path with the band-reject filter.
Claims29
A method of filtering transceiver signals in a mobile terminal, the mobile terminal operable in at least one transmit frequency band and one receive frequency band separated from the transmit frequency band, wherein the mobile terminal has a signal source for providing transmit signal in the transmit frequency band, said method comprising the steps of:
- providing a signal path between the signal source and an antenna;
- and
- providing a band-reject filter in the signal path so as to attenuate signal in the receive frequency band, wherein the band-reject filter comprises:
- at least one series resonator operatively connected between the signal source and the antenna, the series resonator having a first end and an opposing second end, with the first end connected to the signal source;
- at least one shunt resonator connecting between the second end of the series resonator and a grounding point, the shunt resonator and the series resonator forming an L-section;
- and
- at least one inductor connected in parallel with the L-section.
A band-reject filter for use in a mobile terminal, the mobile terminal operable in at least one transmit frequency band and one receive frequency band separated from the transmit frequency band, wherein the mobile terminal has a signal source for providing transmit signal in the transmit frequency band, and a signal path between the signal source and an antenna, said filter comprising:
- at least one series resonator operatively connected to the signal path between the signal source and the antenna, the series resonator having a first end and an opposing second end, with the first end connected to the signal source;
- at least one shunt resonator connecting between the second end of the series resonator and a grounding point, the shunt resonator and the series resonator forming an L-section;
- and
- at least one inductor connected in parallel with the L-section.
A mobile terminal operable in at least one transmit frequency band and one receive frequency band separated from the transmit frequency band, said mobile terminal comprising:
- a signal source for providing transmit signal in the transmit frequency band;
- a signal path between the signal source and an antenna;
- and
- a band-reject filter operatively connected to the signal path so as to attenuate signal in the receive frequency band, wherein the band-reject filter comprises:
- at least one series resonator operatively connected between the signal source and the antenna, the series resonator having a first end and an opposing second end, with the first end connected to the transmission source;
- at least one shunt resonator connecting between the second end of the series resonator and a reference point, the shunt resonator and the series resonator forming an L-section;
- and
- at least one inductance connected in parallel with the L-section.
Dependencies are inferred from the claim text.