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.