Wideband Digital Predistortion for Frequency Multipliers Driven by Nonideal Upconverters

This letter proposes a new technique to calibrate the frequency response of the upconverter in frequency-multiplier-based transmitters. The proposed technique only requires capturing the multiplier output, using the same feedback path needed to train the digital predistortion (DPD) module. In addition, this letter proposes a low-complexity piecewise-based DPD model to compensate for the multiplier nonlinearity. Experiments carried out on a millimeter-wave (mm-wave) frequency doubler showed excellent output signal quality with a 400-MHz modulation bandwidth.