A low-power CMOS chipset for spread spectrum communications

In future personal communication services, high-bandwidth multimedia data will be delivered over wireless pico-cellular networks to high densities of users. The system described here is designed to simultaneously supply 1 Mb/s to up to 50 users in a single cell, requiring a system bandwidth in excess of 50 Mb/s. The use of spread-spectrum techniques, in particular direct sequence code-division multiple access (CDMA), provides a multiple-access strategy to maintain parallel, separate streams of real-time data to all users, and to reduce sensitivity to multipath, narrow band fades, and interference present in the radio environment. Three chips in standard digital 0.8 /spl mu/m CMOS technology implement the critical parts of a spread spectrum transceiver: the digital modulator; the analog receiver front-end and ADC; and the digital receiver baseband processor. The transmit system transmitter is based loosely on the US IS-95 digital cellular CDMA standard, but at more than an order of magnitude higher date rate.