A 4.2Gb/s 10x OSR Adaptive Equalizer Using 1.4x Fractional Sampling Clock

This paper describes a 4.2Gb/s adaptive equalizer using 1.4x fractional sampling method which has the same resolution effect with conventional 10x oversampling method. Since we use multi-phase sampling clocks which have lower frequency than half data rate frequency, PLL power can be saved more than conventional 10x oversampling. Equalizing filter block controlled by 3 bit gain control code allows 8 different gain boosting settings to equalize up to almost 20 ㏈ at 2.1㎓. From simulation results, this work has demonstrated the resolution of 1.4x fractional sampling can be as high as those of 10x oversampling. Fabrication is being progressed in 0.13 ㎛ process.