40 Mbit/s adaptive MLSE equalizer LSI and its performance in 5 GHz-band transmission system

The authors have developed a single chip, 40 Mbit/s operation, 3-tap MLSE equalizer LSI. The LSI supports burst operation and is available for both QPSK and π/4-QPSK modulated signals. This paper shows the performance of a 5 GHz-band 40 Mbit/s experimental system using this equalizer LSI. The main results are as follows. (1) The implicit diversity gain offered by the equalizer is 12 dB at the BER of 10^-3. (2) The gain obtained in 2-branch diversity reception is 6 dB at a BER of 10^-3. (3) In single branch operation, no error floor is observed when the BER is higher than 10^-4. Furthermore, 2-branch diversity reception limits the irreducible bit errors to one-tenth that of single branch reception. (4) The DC offset compensator effectively minimizes the degradation introduced by the DC offset caused by the imperfection of the demodulator. (5) The same performance is observed for both modulation schemes. The LSI can be used in wide band wireless applications like indoor wireless LAN systems and wide area wireless local loop systems