  In this work we propose a new scheme for semi-passive Wake-Up Receiver
circuits that exhibits remarkable sensitivity beyond -70 dBm, while
state-of-the-art receivers illustrate sensitivity of up to -55 dBm. The
receiver employs the typical principle of an envelope detector that harvests RF
energy from its antenna, while it employs a nano-power operation amplifier to
intensify the obtained signal prior to the final decoding that is realized with
the aid of a comparator circuit. It operates at the 868 MHz ISM band using OOK
signals propagated through LoRa transceivers, while also supporting addressing
capabilities in order to awake only the specified network's nodes. The power
expenditure of the developed receiver is as low as 580 nA, remaining at the
same power consumption levels as the state-of-the-art implementations.
