A GSM modulator using a ΔΣ frequency discriminator based synthesizer

This paper describes a new transmitter architecture suitable for GSM modulation. The technique is based on direct modulation of a high resolution ΔΣ frequency discriminator based synthesizer to produce the modulated RF signal without any up-conversion. The advantage of this architecture is that it does not require mixers or D/A converters to generate the in-phase and quadrature signals as in conventional GSM transmitters. This eliminates many of the analog problems associated with mixing and filtering and results in an architecture suitable for monolithic integration