Low supply voltage operation of 40-Gb/s full-rate 4:1 multiplexer based on parallel-current-switching latch circuitry

We implemented new circuit topology, a parallel-current-switching latch, in a full-rate 4:1 multiplexer using InP-HBT technology. This is the first report of this technology, which resulted in 40-Gb/s error-free operation with a power dissipation of only 1 W at a supply voltage of 1.8 V. This voltage is as low as that of high-speed CMOS I/O circuits. This circuit topology is capable of high-speed (>40 Gb/s) selector operation with a large clock phase margin (>200 deg) at a supply voltage as low as 1.3 V using bipolar-based devices that require a relatively large supply voltage. Demultiplexing operation was also confirmed for the D-F/F with this circuit technology at a data rate of up to 110 Gb/s with a 1.8-V supply voltage.