Enabling Digital Predistortion in High Fractional Bandwidth Cellular Multiband Scenarios with Direct-Sampling and Real-Valued Signals

As we increase the fractional bandwidth of a cellular multiband system, at a certain point, the even-order distortion components start to fall inside nearby bands. To enable multiband systems to operate at high fractional bandwidth while still respecting standard requirements with high throughput, one must control these unwanted emissions as well. In this paper, a novel digital predistortion model is presented, capable of canceling both odd- and even-order distortion components. This technique explores the commonly used high-sampling rate RF-DACs/RF-ADCs, but in direct-sampling mode, where up- and down-conversion blocks are bypassed. It processes real-valued signals and the computational complexity is comparable to its complex-valued counterpart, while improving the linearization performance.