Patent ID: 6256511
Filing Date: 2001-07-03
Classification: H04B

Abstract:
A radio front end transceiver operable to receive and transmit radio signals in different frequency bands and modulation formats, the transceiver comprising:(i) a first receive path arranged to receive signals of a first modulation format at a first radio frequency band;(ii) a second receive path arranged to receive signals of a second different modulation format at a second different radio frequency band;(iii) a first transmit path arranged to transmit signals of the first modulation format and first radio frequency band;(iv) a second transmit path arranged to transmit signals of the second modulation format and second radio frequency band;(v) circuitry for conversion between the respective radio frequency band and an intermediate frequency provided in each of the paths;(vi) intermediate frequency circuitry for conversion between the respective intermediate frequency and baseband provided in each of the paths, wherein at least some of the intermediate frequency circuitry is common to both receive paths and at least some of the intermediate frequency circuitry is common to both transmit paths; and wherein the intermediate frequencies are different for the different modulation formats; said intermediate frequency circuitry comprising separate channel filters for the different modulation formats and wherein the transceiver further comprises:(vii) a dual loop frequency synthesiser arranged to derive local oscillator frequency bands suitable for use by the intermediate frequency circuitry on each of the paths; and wherein the transmit and receive local oscillator frequency bands are arranged to overlap, by switching intermediate frequencies, whereby the tuning range is limited.