Method for generating frequencies in a direct conversion transceiver of a dual band radio communication system, a direct conversion transceiver of a dual band radio communication system and the use of this method and apparatus in a mobile station

A dual band direct conversion transceiver, in which

• a first frequency band comprises a first transmission frequency band and a first reception frequency band, and a second frequency band comprises a second transmission frequency band and a second reception frequency band,
• wherein the direct conversion transceiver comprises a frequency synthesizer (12), means (13, 14) for generating transmission channel frequencies (LO2) of the first frequency band and for generating reception channel frequencies (LO1) of the first frequency band, and means (13, 14, 28, 31) for generating transmission channel frequencies (LO2) of the second frequency band and for generating reception channel frequencies (LO1) of the second frequency band, wherein the frequency band of the frequency synthesizer (12) comprises at least a first reception frequency band, whereby reception channel frequencies (LO1) of the first frequency band are generated with the frequency synthesizer (12), transmission channel frequencies (LO2) of the first frequency band are generated by mixing the essentially constant mixing frequency (LO4) with a frequency generated with a frequency synthesizer (12), reception channel frequencies (LO1) of the second frequency band are generated by multiplying a frequency (LO3) generated with the frequency synthesizer (12) by a constant coefficient, and transmission channel frequencies (LO2) of the second frequency band are generated by mixing the essentially constant mixing frequency synthesizer (LO4) with the frequency (LO3) generated with the frequency synthesizer (12) and by multiplying the frequency generated as the mixing result by a constant coefficient.

A dual band direct conversion transceiver in which:

• a first frequency band comprises a first transmission frequency band and a first reception frequency band, and
• a second frequency band comprises a second transmission frequency band and a second reception frequency band,
• wherein the direct conversion transceiver comprises a frequency synthesizer (12), means (14, 28, 36) for generating reception channel frequencies (LO1) of the first and second frequency band, and means (14, 31, 37) for generating transmission channel frequencies (LO2) of the first and second frequency band, wherein the frequency band of the frequency synthesizer (12) comprises at least a first reception frequency band, whereby reception channel frequencies (LO1) of the first frequency band are generated with the frequency synthesizer (12), transmission channel frequencies (LO2) of the first frequency band are generated by mixing the essentially constant mixing frequency (LO4) with a frequency generated with a frequency synthesizer (12), reception channel frequencies (LO1) of the second frequency band are generated by multiplying a frequency (LO3) generated with the frequency synthesizer (12) by a constant coefficient, and transmission channel frequencies (LO2) of the second frequency band are generated by mixing the essentially constant mixing frequency synthesizer (LO4) with the frequency (LO3) generated with the frequency synthesizer (12) and by multiplying the frequency generated as the mixing result by a constant coefficient.

A method for generating frequencies in a transceiver of a radio communication system operating in a set of communication bands including a plurality of transmission bands and a plurality of reception bands, wherein the method provides for generation of frequencies for respective ones of the bands by steps of:

• applying a reference signal from a reference oscillator to a phase locked loop, said applying step including a step of scaling a first frequency of the reference signal by a first scale factor;
• within the phase locked loop, scaling a second frequency of a signal outputted by a voltage controlled oscillator (VCO) by a second scale factor;
• mixing the VCO signal with the reference oscillator signal to provide a mixed signal having a third frequency offset from both of said first and said second frequencies;
• and
• employing said second and said third frequencies as reference signals for operation of said set of communication bands.

A dual band direct conversion transceiver, operative with a set of communication bands including a plurality of transmission bands and a plurality of reception bands, the transceiver including circuitry for generation of reference signals for operation of said set of communication bands, said circuitry comprising:

• a reference oscillator, a first frequency scaling means, a mixer, and a phase locked loop (PLL) comprising a voltage controlled oscillator (VCO) and a second frequency scaling means;
• wherein said first scaling means couples said reference oscillator to said PLL for scaling a first frequency of a signal outputted by said reference oscillator by a first scale factor;
• said second scaling means is operative within said PLL to scale a second frequency of a signal outputted by said VCO by a second scale factor;
• and
• said mixer is operative to mix the VCO signal with the reference oscillator signal to provide a mixed signal having a third frequency offset from both of said first and said second frequencies.