High speed 8:1 multiplexer and 1:8 demultiplexer implanted with AlGaAs/GaAs HBTs

Development of an 8:1 multiplexer and 1:8 demultiplexer implemented with AlGaAs/GaAs heterojunction bipolar transistors is reported. The circuits were designed for lightwave communications and operate at data rates above 6 Gbit/s. The intrinsic speed of the circuits can be further increased by design changes with more power allocated per gate and better time matching at the high-speed ends. The circuit design, fabrication, and test results are presented. >