Abstract: A method and system for quadrature modulation and digital-to-analog conversion of a sampled and digitally represented complex baseband signal which permits the use of simple, power-saving, accurate and effective digital signal processing up to a very high intermediate frequency. The invention requires an input signal in the form of an oversampled complex baseband signal. The inphase (I) and quadrature-phase (Q) components of this signal are first quantized to preferably 1 bit per sample, e.g., with the aid of &Sgr;&Dgr; modulation, so that the quantization noise is essentially forced outside the frequency band of the working signal. Then the sampling rate of the quantized versions of I and Q is converted to four times the desired carrier frequency, before the signal is quadrature modulated with a signal frequency exactly equal to one quarter of the final sampling rate.