A low power 12Gb/s single-stage 1 ： 4 demultiplexer （DEMUX） applied in SONET OC-192 is realized in TSMC＇s mix-signal 0. 25μm CMOS. All of the circuits are in source coupled FET logic （SCFL） to achieve as high a speed as possible and suppress common mode distortions. This DEMUX is featured for achieving singlestage demultiplexing by using a quarter-rate IQ clock. This method not only reduces the components of the DEMUX but also lowers its power dissipation. The fabricated DEMUX operates error free at 12Gb/s by 231 - 1 pseudorandom bit sequences in on-wafer testing. The chip size is 0. 9mm × 0.9mm and the power dissipation is only 210mW with a single 2.5V supply.
A high integrated monolithic IC, with functions of clock recovery, data decision, and 1 ： 4 demultiplexer,is implemented in 0.25μm CMOS process for 2.5Gb/s fiber-optic communications. The recovered and frequency divided 625MHz clock has a phase noise of -106.26dBc/Hz at 100kHz offset in response to a 2.5Gb/s PRBS input data （2^31-1）. The 2.5Gb/s PRBS data are demultiplexed to four 625Mb/s data. The 0.97mm× 0.97mm IC consumes 550mW under a single 3.3V power supply （not including output buffers）.
