High Sensitivity Near-zero Power Wakeup Receiver for Backscattering RF Tags

We present a wake-up receiver amenable to integration in a node of RF backscattering tag-to-tag network. A high input impedance of a passive envelope detector (ED) is accomplished by backward bias that improves the passive voltage gain. Two differential outputs are ac-coupled to a baseband amplifier that operates in the subthreshold region. We develop a closedform model of the passive ED in order to predict the output and ripple voltages and therefor the receiver's sensitivity. The wakeup receiver is implemented in 180 nm CMOS technology and consumes 2 nW with 0.8 V supply voltage while demodulating 915 MHz amplitude-shift keying (ASK) signal with data rate of 10 kbps. The receiver demonstrates -67.98 dBm sensitivity in resolving ASK modulated signal.