A near-zero-power fully-differential Wake-Up Circuit
A envelop detector first topologies with baseband amplification stage is suitable for ultra-low power backscattering tag design. The full-differential envelop detector increases gain by 3dB. The adaptive signal resolution is realized by modifying the gain of baseband amplifer and the bits of correlation circuit.
Self-biased low modulation index ASK demodulator
A demodulator design comprising a self-biased common-source based envelop detector that provides sufficient conversion gain. A two stages dynamic comparator is utilized to further save power.
Measurement doppler shifts between tags in a backscattering tag-to tag network
Passive tags can track each other in a backscattering tag-to-tag network (BTTN). In the PCB prototype, the passive tags remove on-board radio transceiver and communicate each other by backscattering techonlogy. In our lab, we examine the received signal amplitude over multiple backscattering phases and measure inter-lag distance. The measured doppler shifts with approximately is the same accuracy as that achieved by active conventional RFID readers. Our median tracking error based on data from two tags is only about 2.5 cm.
A demodulator design comprising a self-biased common-source based envelop detector that provides sufficient conversion gain. A two stages dynamic comparator is utilized to further save power. 
Passive tags can track each other in a backscattering tag-to-tag network (BTTN). In the PCB prototype, the passive tags remove on-board radio transceiver and communicate each other by backscattering techonlogy. In our lab, we examine the received signal amplitude over multiple backscattering phases and measure inter-lag distance. The measured doppler shifts with approximately is the same accuracy as that achieved by active conventional RFID readers. Our median tracking error based on data from two tags is only about 2.5 cm.