Subharmonically Pumped Millimeter-Wave Upconverters Based on Heterostructure Barrier Varactors

A heterostructure barrier varactor subharmonic upconverter is investigated for the first time. Odd sidebands are suppressed due to the symmetric capacitance-voltage (C-V) characteristic of the varactor and high output power is possible through epitaxial stacking of barriers. The upconverter is pumped using a millimeter-wave local oscillator, and can be used as a transmission-type double-sideband suppressed carrier modulator. The initial measured conversion loss is 8-16 dB at 100 and 200 GHz. The results are significantly improved by using external impedance tuners, which is verified through both simulations and measurements