Efficient linear transmission of complex waveforms at 216 GHz using nonlinear multiplier chains

A solid-state 216-GHz communication link is presented. It utilizes a novel mixer-less transmitter technique to achieve efficient complex modulation using frequency multipliers (which are inherently nonlinear). The transmitter operates with coherent power combining of two frequency multiplier chains to achieve precise linear amplitude and phase modulation despite the strong nonlinearity of the multipliers and the saturated power amplifiers. A 16-QAM modulation signal is demonstrated with a transmitted output power of 100 mW.