TABLE OF CONTENTS An overview of different transmit architectures is given. The major scope are the concepts used in the GSM system. A comparison with respect to integration level and system cost is given. The modulation loop concept commonly used today is discussed in detail, with respect to implementation details and trade-offs.
The rapidly growing mobile communication market requires increasing the efforts to achieve higher integration levels. The ultimate goal is the integration of a complete mobile on a single die preferably on a CMOS die. The example given in Fig. 10.1 is still a dream. Today, we are far away from this goal. RF CMOS is more or less a research topic, although there are already a lot of publications dealing with this subject [1] [6]. A demonstration of a fully functional GSM-like high-end system is not yet in sight. This would require a circuit which achieves the system specifications with respect to process, temperature and supply variations. Moreover, this target has to be met in a real environment, including on-chip bias circuitry. For these reasons, we are presently far away from integrating the RF parts of high-end systems on a single CMOS die.
It has not been demonstrated yet how to integrate large digital blocks along with analog RF blocks. Baseband digital signal processing typically requires a large die area even in advanced technologies. It...
