Spur Cancellation Digital Predistortion for HF Transmitters with Carrier Aggregation

Bulky and lossy multiplexers are used in the analog domain to implement conventional high-frequency (HF) transmitters with carrier aggregation (CA). In this paper, a spur cancellation digital predistortion (SC-DPD) technique is developed for HF transmitters together with a multiplexer-less CA scheme. The proposed SC-DPD scheme effectively mitigates out-of-band harmonics, cross-band modulation distortion (CMD), and intermodulation distortion (IMD) at the same time. Using a quad-band signal, a number of experiments were carried out on an HF power amplifier (PA). The proposed SC-DPD scheme resulted in the cancellation of all nonlinear spurs that fell below -52 dBc, including CMD components and harmonics. The error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were both enhanced by 25 dB and 23 dB, respectively.