Monolithic coplanar transmission lines loaded by heterostructure barrier varactors for a 60 GHz tripler

Nonlinear transmission lines (NLTLs) loaded by InP-based heterostructure barrier varactors (HBVs) have been fabricated in a monolithic coplanar technology for the first time. The devices were designed for a tripler with a 60 GHz; output frequency. The single HBV diodes, fabricated in a dual barrier scheme, exhibit a capacitance ratio of 6:1, a normalized capacitance of 1.4 fF/μm² and a voltage breakdown in excess of 10 V. Under moderate pumping (20 dBm), a tripling operation with 30% bandwidth was demonstrated with unsaturated conversion efficiency (1%) for a eight-HBV prototype.