A quad-band low power single chip direct conversion CMOS transceiver with ΣΔ-modulation loop for GSM. - Edmund Götz; Hans Krobel; Gunter Marzinger; Bernd Memmler; Christian Muenker; Burkhard Neurauter; Dirk Romer; Jorn Rubach; Werner Schelmbauer; Markus Scholz; Martin Simon; Ulrich Steinacker; et al. (ESSCIRC, 2003)