Millimeter and sub-millimeter wave tunerless planar varactor frequency upconverters

The development of high frequency sources has been a persistent challenge. A frequency upconverter can be used to generate frequency tunable sidebands from a fixed source like a FIR cavity laser. The design and measurement of tunerless Schottky planar varactor and heterostructure barrier varactor (HBV) frequency upconverters are presented in this dissertation. The integration of the diode with the embedding circuit enhances mechanical robustness and makes the circuits easy to handle compared with the whisker-contacted diode architecture. A nonlinear analysis was used to determine the optimum varactor diode parameters. First, 200 GHz and 600 GHz Schottky varactor upconverters were designed and implemented. Similar performance was measured for the ohmic and non-ohmic circuits. Therefore, the non-ohmic contact circuit is a better choice for submillimeter wave applications. The 200 GHz Schottky upconverter S-parameters were also measured to verify the simulation. The measurement of the upper sidebands for 200 GHz and 600 GHz show 7--10 dB and 10--20 dB conversion loss respectively over a 10 GHz tuning range.; During the research on Schottky varactor frequency upconverters, heterostructure barrier varactors (HBVs) were found to be potential devices for use in upconverters. They are investigated for the first time to realize subharmonic frequency upconverters.; Though HBV upconverters have many advantages at microwave and millimeter range, it is difficult to scale them to the THz range due to the fabrication limitations. Finally, the Schottky varactor upconverter was scaled to 1.6 THz. Based on optimization and practical fabrication limitations, the 1.6 THz upconverter circuit quartz substrate thickness is chosen to be 10 mum and the anode diameter is determined to be 1 mum. Incorporating the non-ohmic contact technique with a surface channel etch (SCE) eliminating process, the 1.6 THz integrated circuits were fabricated in University of Virginia with high yield. The conversion loss was measured to be approximately 22 dB with 40 muW output sideband power at 10 GHz microwave pump. A novel phase shift measurement for 1.6 THz upconverter using standing wave method is proposed and used to corroborate the results.