Millimeter-Wave Wideband Hybrid Loadpull Measurement Technology

With the advent of mmWave 6G communications, it has become crucial to characterize devices and circuits under varying source- and load impedances at conditions that mimic these emerging applications. 

While still useful, it is no longer sufficient to perform such characterizations at single excitation frequencies or across a narrow bandwidth (<100 MHz). Instead, characterizations are to be performed over realistic signal bandwidths which are multi-GHz in emerging mmWave communication applications. Achieving a predefined impedance characteristic over a multi-GHz bandwidth cannot be achieved by passive loadpull, but requires active or hybrid loadpull. Some commercial solutions exist at microwave frequencies, but not reaching yet the mmWave band. The major reason is the need of a frequency multiplier (FreqX) in the signal generation path in order to reach W-band (and beyond), and this device strongly introduces unwanted distortion. The aim of this PhD research is synthesizing a predefined wideband load in the mmWave band by properly predistorting the load excitation as to compensate for the nonlinearity induced by the FreqX. The challenge is that such pre-distortions are to be achieved simultaneously at the source and load side, and therefore adding the complexity of synchronization and real-time monitoring of the realized wideband loads.