Proof-of-Concept of Millimeter-wave RF Beamforming Transmitter Architecture Employing Frequency-Multiplier-Based Up-converters

This paper proposes a millimeter-wave RF beamforming transmitter architecture that employs frequency multipliers (FMs) as frequency up-converters to avoid the challenges associated with the signal and local oscillator distribution networks that intensify with the increase of operating frequency. The proposed architecture incorporates a single-input single-output (SISO) digital predistortion (DPD) scheme that is specifically devised to mitigate the nonlinear distortions exhibited by the cascade of FMs and power amplifiers (PAs). Proof-of-concept experiments conducted on a line-up comprised of an off-the-shelf frequency doubler and an 8x8 array, operating at an output frequency of 28 GHz, confirmed the capacity of the proposed architecture to transmit 200 MHz orthogonal frequency-division multiplexing signals with an error vector magnitude and adjacent channel power ratio better than 1.6% and 45 dB, respectively, while achieving an effective isotropic radiated power of 46.3 dBm.