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.