A 6.93 µW wake-up circuit for active RFID Tags

As the popularity of the active RFID technology continues to surge for its many advantages, its fatal flaw of power consumption is, however, an inherently limit of its application. To hurdle through the energy limitation, a low-power wake-up circuit for active RFID Tags is proposed in this paper. The circuit, performing as ASK demodulator, employs an OTA, a peak detector, a RC filter, a comparator, and a bias circuit. To lower power consumption, methods of using MOS transistors working in weak inversion region are implemented in this design. The test chip is fabricated in 0.35 μm CMOS process. Its total area is 0.14 mm × 0.17 mm. Measurement result shows that the dc current is 2.1 μA for a supply voltage of 3.3V. The carrier frequency varies from 10 kHz to 1 MHz and the data rate is from 1 kb/s to 10 kb/s. The sensitivity is 50 mVpp.