A Low Voltage and Ultra-low Power Reference Circuit for Passive UHF RFID Tag Chip

This paper describes a low voltage and ultra-low power reference circuit to generate voltage reference and current reference for passive UHF RFID tag chip based on subthreshold CMOS. It adds the threshold voltage with negative temperature coefficient (TC) and the thermal voltage with positive TC, to produce reference voltage and current with zero TC. The voltage reference circuit outputs voltage of 411 mV, featuring a TC of 17.1 ppm/°C to 43.1 ppm/°C from -25°C to 100 °C. And the current reference outputs 101 nA of current with a TC of 15.4 ppm/°C to 115.8 ppm/°C. The power consumption of voltage reference and current reference are 188.1 nW and 366.3nW. Because there is multiplexing of circuits, the total power consumption is 463 nW, and 513 nW at worst.