Study and design of a front-end of a UHF RFID Tag in 0.18 μm CMOS technology

This paper presents the study and design of a modulator (front-end) of a UHF RFID tag in CMOS technology. The analog front-end works like this: A rectifier extracts a DC voltage from the RF supplied by the tag. A voltage regulator follows the rectifier and its role is to obtain a stable supply voltage Vdd for the digital part and the analog front-end. In addition, the ASK demodulator (ASK: Amplitude Shift Keying) extracts the data symbols embedded in the carrier waveform (data input).Backscatter modulation is achieved by switching the input impedance between two reflection states determined by the data output signal. The main objective is to simulate a modulator of the load impedance by which the Tag radiates a modulated signal back to the RFID reader using ADS simulation software and TSMC RF CMOS 0.18μm process library.