Patent ID: 9747538
Date: 2017-08-29
CPC Classifications: G06K,Y02D

Claim:
1. A radio-frequency (RF) tag for use in a sensor network, the RF tag comprising: an energy harvesting unit operable to convert incident RF energy to direct current (DC); a storage unit operable to store recovered DC power; a passive wakeup pattern detector operable to generate an interrupt in response to detecting a set of one or more subcarriers; one or more sensors for sensing; a communication mechanism; a microcontroller coupled to the energy harvesting and storage units, and the one or more sensors, the microcontroller operable to wake up from a sleep state in response to the interrupt and cause the communication mechanism to exchange data wirelessly with a second communication mechanism while powered by energy previously harvested and stored by the energy harvesting and storage unit; an antenna; a first impedance matching circuit directly connecting the antenna to the passive wakeup pattern detector; a switch connected to the antenna; a second impedance matching circuit, separate from the first impedance matching circuit, on an output of the switch; and a demodulator coupled to the switch via the second impedance matching circuit.