1.2 Integrated circuit technologies for wireless systems

Low-cost miniaturised transceivers can only be achieved by advanced IC technologies. Today's microelectronics is moving towards SoC (system on a chip) implementation for communication and information systems. There have been several competing IC technologies, which include CMOS, BiCMOS, Bipolar, SiGe and GaAs. Low-cost and readily available CMOS has to date been the mainstream technology used in many areas, including computers, video, image and display systems, DSL and cable modems and circuits for wired communications, RF circuits and transceivers for wireless communications, and even high-speed circuits and systems for optical communications. Recently CMOS has been demonstrated to be a viable technology for very high bit rate broadband circuit design at over 10 Gb/s in highly integrated systems. Meanwhile advances in device scaling and doping profile optimisation have also resulted in SiGe bipolar transistors with impressive performance, including cut-off frequencies in the region of 200 GHz. This makes them an attractive choice for applications at 40 Gb/s and above.

Modern microelectronic circuits and systems are mainly based on submicron and deep-submicron-CMOS technologies. Whilst pushing the limits of CMOS, preparation for the post-CMOS era is well under way. Many other potential alternatives such as MEMS have been pursued. Nanoelectronics and nanotechnologies have recently emerged and have been widely investigated. They will certainly become the key enabling technologies in future advances. With the current research trend, nano CMOS technology may soon be available for integrated communication circuits and systems.

In this book, CMOS technology is used throughout for implementation of transceiver, analogue and RF circuits for wireless communications, because of the promising RF performance of submicron-CMOS, together with the advantages of low cost and ease of integration with baseband digital circuitry for SoC.