A passive UHF RFID tag chip with a dual-resolution temperature sensor in a 0.18μm standard CMOS process

This paper presents a passive EPC Gen-2 UHF RFID tag chip with a dual-resolution temperature sensor. The chip tag integrates a temperature sensor,an RF/analog front-end circuit,an NVM memory and a digital baseband in a standard CMOS process.The sensor with a low power sigma-delta（ΣΔ） ADC is designed to operate in low and high resolution modes.It can not only achieve the target accuracy but also reduce the power consumption and the sensing time.A CMOS-only RF rectifier and a single-poly non-volatile memory（NVM） are designed to realize a low cost tag chip.The 192-bit-N VM tag chip with an area of 1 mm;is implemented in a 0.18-μm standard CMOS process.The sensitivity of the tag is -10.7 dBm/-8.4 dBm when the sensor is disabled/enabled.It achieves a maximum reading/sensing distance of 4 m/3.1 m at 2 W EIRP.The inaccuracy of the sensor is -0.6℃/0.5℃（-1.0℃/1.2℃） in the operating range from 5 to 15℃in high resolution mode（-30 to 50℃in low resolution mode）.The resolution of the sensor achieves 0.02℃（0.18℃） in high（low） resolution mode.