Fully integrated passive UHF RFID tag with temperature sensor for environment monitoring

A long range passive tag with temperature sensor in 0.35 mu m CMOS process has been presented. It contains five sections: RF front-end circuit, digital logical circuit, temperature sensor, a low power SAR ADC and memory circuit. The RF section contains a voltage rectifier, a voltage regulator, a PWM demodulator, a PSK backscatter modulator, and a local oscillator has been calibrated by the reader´s emitting signals. The circuits of the chip work at multi supply voltage for lower power, and the total current dissipation is 15.4 mu A. A low-power 8 bit successive approximation analog to digital converter (ADC) is used to quantize the temperature output. The error of the temperature quantity output is plusmn 2degC in the range of -10 - 120degC.