An 868 MHz 7.5 µW wake-up receiver with −60 dBm sensitivity
In wireless sensor networks (WSNs), batteries are unlikely to be replaced or recharged once they get depleted, because of costs and feasibility. In a typical application, sensor nodes should be accessible and able to respond within a defined period of time, especially in real-time applications. However, the idle listening of the radio wastes most of the energy since the radio transceiver is constantly active. On the other hand, putting it into sleep state disconnects the node from the network. To cope with such a challenge, an ultra-low-power radio receiver referred to as a wake-up receiver (WuRx) handles the idle listening while keeping the main radio completely off. A WuRx consumes much less power than the main transceiver and triggers an interrupt only when a packet with a user-defined address is received. Embedding such a device enables better event-triggered applications where real-time behavior is required and a longer lifetime is mandatory. The proposed WuRx features practical sensitivity and includes the minimum number of active components in order to remain within the power budget. In this paper, an ultra-low-power WuRx with a power of 7.5 µW and a sensitivity of −60 dBm is developed. The decoding process of 16 bit of a wake-up packet (WuPt) takes less than 15 ms.