A single chip PHY COFDM modem for IEEE 802.11a with integrated ADCs and DACs

This chip, fabricated in a 0.25/spl mu/m 5M1P CMOS process with 3.7M transistors, implements a fully-compliant IEEE 802.11a PHY modem. The IEEE 802.11a standard provides for wireless local area networks (WLANs) with a physical layer based on coded orthogonal frequency domain multiplexing (COFDM) modulation, delivering data rates up to 54Mb/s, operating in the 5GHz UNII frequency bands. The article outlines the role of a physical layer (PHY) modem in such a WLAN system. The PHY modem lies between a medium access controller (MAC) and a 5GHz radio transceiver, and is responsible for demodulating and modulating a baseband analog signal with data from the MAC. In 802.11a the baseband signal is a 64 subcarrier COFDM signal with BPSK, QPSK, QAM16 or QAM64 modulated subcarriers.