An 11-tap 0.9- mu m CMOS digital transversal equalizer for digital radio

Abstract

A 0.9- mu m CMOS VLSI device was designed and developed to perform as an adaptive transversal equalizer for digital radio. The device contains an 11-tap multiply-add structure complete with control hardware for 12-b coefficients. Void of any pipelining, the device is guaranteed for 27-MHz operation, and it has demonstrated speeds in excess of 40 MHz. A digital radio modem has been designed by AT&T using the VLSI device and is now being manufactured for a 64-QAM (quadrature amplitude modulation) 4-GHz radio system. BER (bit error rate) performance versus S/N ratio was within 1.8 dB of theoretical (no error correction) at a BER of 1*10/sup -8/. M-curves were measured for the 20-MHz channel and were very close to theoretical. Finally, modem acquisition statistics were tabulated under various channel distortions, with the average time of acquisition being less than 200 ms.<>