Analog Frontend for a Passive 5.8-GHz RFID Transponder in 130-nm CMOS Technology

We present a 5.8-GHz RFID transponder frontend. It consists of a 3-stage charge pump/rectifier circuit, a demodulator circuit featuring the same charge pump topology, a single transistor modulator, allowing backscatter modulation, an LC-matching network, which matches the impedance of the transponder to a 175-Omega antenna, as well as ESD and overvoltage protection circuitry. The transponder frontend was characterized by wafer prober measurements yielding a sensitivity of -11 dBm and reflection coefficients of -18 dB when the modulator is in off-state and -5 dB when the modulator is in on-state. The RFID-frontend was also integrated into a demonstrator PCB, featuring a 175-Omega patch antenna. With the demonstrator PCB, demodulation of incoming signals, as well as backscatter modulation, could be demonstrated. The intended application is the electronic identification of sterile goods in medical facilities to comply with the new European medical device directive 2017/745.