A 10 Gb/s demultiplexer IC in 0.18 /spl mu/m CMOS using current mode logic with tolerance to the threshold voltage fluctuation

A 10 Gb/s 1:8 Demultiplexer (DEMUX) IC for optical-fiber-link systems uses a 0.18 /spl mu/m CMOS process for the first time. A differential logic like MOS current mode logic (MCML) is suitable for 10 Gb/s systems because of its switching speed and power consumption. The maximum operating frequency of MCML is, however, reduced by fluctuation of the threshold voltages (V/sub TH/) of the differential pair transistors. This V/sub TH/ fluctuation is a serious problem for deep submicron MOSFETs. The present circuit uses feedback MCML which is more tolerant to V/sub TH/ fluctuation than conventional MCML technology.