Schottky diode integrated circuits for sub-millimeter-wave applications.

摘要

Using Schottky varactor diodes on GaAs, sampling circuits with bandwidths of 725 GHz have been fabricated and measured. The sampling circuits are integrated with nonlinear transmission lines, which are traveling-wave structures that generate the subpicosecond electrical pulses necessary to strobe the sampling circuits. This bandwidth was obtained by combining a number of technologies had been developed: varactor diodes with RC cutoff frequencies above 4 THz, coplanar waveguide transmission lines with the center conductor elevated off the substrate, and ways of minimizing all parasitics. Other applications of these technologies include a 100 Gbit/sec mux/demux circuit and 200 GHz traveling wave amplifiers.;By applying what had been learned from the varactor diodes, a novel device structure, a Schottky-collector resonant tunneling diode (RTD), was developed in the AlAs/GaAs system. By changing the collector from an ohmic to a Schottky contact, the scaling laws that are used for other devices are now applicable to the RTD. With 0.1 m Schottky fingers, a maximum frequency of oscillation of 900 GHz was attained, more than twice that of a conventional RTD. By applying this technique to AlAs/InGaAs on InP, RTDs with fmax above 2 THz have been tested. The long range goal of the project is to build oscillator arrays for generating power above 1 THz.