Digital transceiver

A digital up-converter usable in a radio communications system for transmitting digital base-band signals to up-convert an incoming digital base-band signal into a digital band-pass signal, the digital base-band signal comprising an in-phase component and a quadrature component, comprising:

• at least two over-sampling units each comprising a plurality of FIR low-pass filters connected to a sample and hold circuit to over-sample the incoming in-phase component and the incoming quadrature component at an over-sampling ratio of 1/2NT, wherein 1/2NT is an arbitrary integer;
• at least two time-discrete sigma-delta low-pass modulators connected to the over-sampling units to convert the over-sampled in-phase component and the over-sampled quadrature component into a single bit/1.5 bit format which is a bi-serial signal representing three levels as a parallel set of a zero-bit signal and a sign-bit signal, wherein the at least two time-discrete sigma-delta low-pass modulators are resized as systolic arrays;
• at least one quadrature modulation unit for performing quadrature modulations to convert the incoming in-phase component and the incoming quadrature component in single/1.5 bit format into a digital band-pass signal available in single bit format or 1.5 bit format at a output of the digital up-converter.