Recent Advances in Frequency-Multiplier-Based Transmission of mm-Wave Modulated Signals

This workshop starts with a brief analysis of the non-linear behavior of Frequency-Multiplier (FM) based RF beamforming transmitters (TXs) over a wide range of steering angles that culminates with a dual-input behavioral model. Next, it highlights and justifies the very distinctive feature of FM-based RF beamforming arrays have reduced sensitivity to load modulation when compared to last-stage power-amplifier (PA) based arrays. Then, it introduces a Single-Input Single-Output (SISO) Digital Predistortion (DPD) scheme to linearize FM-based RF Beamforming TX arrays over wide steering range. Furthermore, recent major system-level improvements to maximize the viability of FM-based beamforming TXs will be described. These will include, for example, new techniques to: i) reduce the required sampling-speed of the digital-to-analog converters, ii) calibrate for the non-ideal frequency response of the up-converter stage without resorting to a dedicated observation receiver. Proof-of-concept experiments conducted using frequency doubler-based RF beamforming TXs will be presented and over-the-air measurement data will be depicted in support of FM-based RF beamforming TXs as a competitive architecture for directive transmission of modulated signals at carrier frequencies that approach the maximum frequency of the chosen semiconductor technology node.