75 GBd InP-HBT MUX-DAC module for high-symbol-rate optical transmission

Abstract— Owing to the spread of broadband applications, data traffic in optical communication networks is continuously increasing. High-symbol-rate optical transmission schemes with advanced multi-level modulation formats, such as M-ary quadrature amplitude modulation (QAM), are now being investigated as to their suitability for future cost-effective 1 Tb/s-class optical transport networks. The IC was designed and fabricated with 0.5 μ m emitter InP-HBT technology. InP HBTs are attractive for making high-speed, high-sensitivity, and high-output-power analogue and mixed-signal ICs because they offer excellent high-frequency performance, high internal voltage gain and a high breakdown voltage. The HBTs employ a thin InP emitter layer suitable for making thin passivation ledge structures and thus for enhancing device reliability. A very thin n-type doped layer is employed in the heterojunction vicinity in order to lower the turn-on voltage, VBE,ON , of the transistor. < final year projects >