A 2.4GHz/915MHz 51µW wake-up receiver with offset and noise suppression

In order to simultaneously optimize network lifetime and latency in wireless sensor networks (WSN), an always-on wake-up receiver (WuRx) can be used to monitor the radio link continuously. For truly autonomous sensor nodes employing energy scavenging, only 50µW power is available for the WuRx [1]. An envelope detector is a popular choice in WuRx because of its low power consumption. However, the detector is always the bottleneck of the receiver sensitivity since it attenuates low level input signal and adds excessive noise. One way of improving sensitivity is to amplify the signal before the detector, for example at RF [2, 3] or IF [4] stages, to enhance the SNR at the output.