This paper proposes a flexible multi-standard digital frontend (DFE) hardware architecture designed for three main low-power wide-area (LPWA) technologies: LoRa, Sigfox, and narrowband-Internet of things (NB-IoT).We demonstrate the feasibility of an unified DFE architecture that fits the requirements of these LPWA technologies. The proposed DFE architecture has been implemented on a Spartan-6 field programmable gate array (FPGA) within a base station receiver, and tested using a universal software radio peripheral (USRP) based platform. We show that the expected performance can be achieved with low hardware complexity, in terms of memory and logic requirements.