To promote WSNs for IoT, energy consumption must be reduced to enable more applications. The power need by a sensor node is governed by the radio component. A wake-up receiver is an ultra-low-power radio receiver. It serves for idle listening whilst leaving the node in sleep state. The main research focus of WuRxs is to reduce energy usage and to improve sensitivity. In this work, active components are carefully used to construct a 7.5 µW WuRx with −60 dBm sensitivity and a latency of 10 ms.