Transceiver with switchable frequency band and bandwidth

A transceiver, which in a Frequency Division Duplex (FDD) mode of operation receives at a first, reception frequency (F1) in a first frequency band and transmits at a second, transmission frequency (F2) in a second frequency band, and in a Time Division Duplex (TDD) mode of operation receives and transmits at a third frequency (F3) in a third frequency band, said transceiver comprising a receiving branch and a transmitting branch, and further comprising:

• in the receiving branch, a first mixer (2) for forming a first intermediate frequency (IF1) from a received frequency (F1, f3) and from a first local oscillator frequency (LO1), and a second mixer (7) for forming a second intermediate frequency (IF2) from the first intermediate frequency (IF1) and from a second local oscillator frequency (LO2);
• and
• in the transmitting branch, a modulator (15) for modulating signals to be transmitted (TXI, TXQ) to a third intermediate frequency (IF3), a third mixer (16) for forming a transmission frequency (F2, F3) from the third intermediate frequency (IF3) and from a fourth local oscillator frequency (LO4),
• said transceiver further comprising first synthesizer means (17) for forming equally high first and fourth local oscillator frequencies (LO1, LO4), second synthesizer means (12), and one of a frequency multiplier or divider (14a, 14b, 14c, 14d, 14e) and switching means (13, 13e) for forming and switching a fourth frequency (FS/M, FS) and an M times multiple of the fourth frequency (FS, M*FS),
• characterized in that the fourth frequency (FS/M, FS) has a magnitude that is an absolute value of a difference between the reception frequency (F1) and the transmission frequency (F2) of the FDD mode of operation divided by (M-1),
• wherein in the FDD mode of operation the fourth frequency (FS/M, FS) is switched to be the third local oscillator frequency (LO3), and said multiple (FS, M*FS) of the fourth frequency is switched to be the second local oscillator frequency (LO2), if the reception frequency (F1) of the FDD mode of operation is higher than the transmission frequency (F2),
• wherein the fourth frequency (FS/M, FS) is switched to be the second local oscillator frequency (LO2), and said multiple (FS, M*FS) of the fourth frequency is switched to be the third local oscillator frequency (LO3), if the reception frequency (F1) of the FDD mode of operation is lower than the transmission frequency (F2),
• and wherein in the TDD mode of operation either the fourth frequency (FS/M, FS) or said multiple (FS, M*FS) of the fourth frequency is switched to be both the second local oscillator frequency (LO2) and the third local oscillator frequency (LO3).