ESS-Bilbao is the Spanish candidature of the future European Spallation Source. As part of the R&D work at the ESS-Bilbao consortium an ion source test stand is currently under construction at the Zamudio technology park in the Basque country (Spain). The first stage of acceleration and beam focus at the ion source LINAC is carried out by a Radiofrequency Quadrupole system driven by a klystron. In order to control the pulsed RFQ field and the RFQ tuning, a novel digital LLRF system based on IQ modulation/demodulation has been designed by the ESS-Bilbao RF group in collaboration with the Electricity and Electronics Department of the UPV/EHU university. In this paper the RFQ specifications and the LLRF design (amplitude, phase and tuning loops) are presented.