The design of a single-chip CMOS 900 MHz spread spectrum transceiver

This is a progress report on one of the first coordinated, large-scale research efforts towards realising a single-chip 900 MHz digital radio. Several factors are responsible for what has been achieved so far. First, this was an example of a simultaneous evolution of the systems architecture with the enabling circuits components, thus allowing for a joint optimisation. This luxury is seldom afforded to circuit designers working to the established specifications of an industry standard, but because our transceiver operates in one of the three Industrial, Scientific, and Medical (ISM) frequency bands opened up by the FCC for unlicensed spread-spectrum use, we could design a unique system architecture. A user of these bands is required to spread the transmitted spectrum by a minimum amount, and to transmit no more than a specified power from the antenna, but is otherwise free to use any modulation scheme or spread-spectrum strategy. Second, it was decided at the outset that the entire transceiver would be integrated in CMOS, which affords an unprecedented flexibility in choosing between an analog or digital implementation of the various receiver blocks. Third, the project has evolved from a close collaboration between analog and digital circuit designers, communication system engineers and antenna designers.