This paper presents the design of an innovative discrete-time (DT) wake-up receiver (WuRx) for short-range wireless sensor networks. A switched-capacitor architecture was adopted to implement a digital filter providing some adjustment of the receiver parameters. The inherent aliasing susceptibility of the digital filter is opposed by the current sampler structure as it performs an anti-aliasing function at the input without the typical external bandpass filter solution. The circuit designed for on-off keying (OOK) modulation at 900 MHz and a data rate of 100 kbps is implemented in 180 nm CMOS. Extracted post-layout simulation results show a sensitivity of-70 dBm and current consumption of 27.7 µA from a 1.2 V supply.