A wide band arbitrary waveform generator which targets sub-6 GHz 5G carrier aggregated transmission schemes is presented. The wanted signal is composed of up to ten aggregated modulated signals distributed over different frequency bands. A piecewise linear approximation of this composite signal is generated, based on the integration of constant current steps into a capacitive load. The implementation of the digital-to-analog core in a 65 nm CMOS technology is depicted; it exhibits a sub- mW consumption and a tiny die area. System simulations are led to confirm its ability to address the generation of various configurations of carrier aggregated signals with respect to the 5G prospects.