Quadrature Amplitude Backscatter Modulator for Passive Wireless Sensors in IoT Applications

Fully passive wireless networks are a key-enabling technologies for the internet of things. Backscatter radios are a hypothesis to design these passive wireless networks. Backscatter modulation allows a remote device to wirelessly transfer information without requiring a traditional transceiver. Instead, a backscatter device leverages a carrier transmitted by an access point or base station. Nevertheless, the traditional approach is to use amplitude shift keying or phase shift keying backscatter solutions which limits the data rate of the sensors, since it transfers only one bit per symbol period. We propose a novel modulator, which employs a Wilkinson power divider with a phase shift in one of the design branch and two transistors acting as switches in order to generate M-quadrature amplitude modulation backscatter modulation. The design strategy for high level order backscatter modulations will be explained and a design approach will be presented in this manuscript.