Wirelessly-Powered Dielectric Sensor With On-Chip Antennas in 180 nm SOI CMOS Process

This paper presents a battery-less mm-sized wirelessly-powered dielectric sensor with on-chip antennas in 180nm SOI CMOS process. The dielectric constant detection is achieved by sensing capacitance change of a capacitor in an oscillator, which causes a shift in the oscillation frequency. The chip harvests electromagnetic energy from a continuous-wave source at 9.8 GHz using an on-chip antenna, which shrinks the whole sensor size to millimetre scale. The design details of the wireless power transferring front-end with integration of an on-chip antenna are reported. The oscillator free-running frequency is from 3.66 to 4 GHz which depends on the material on top of the chip. The chip radiates back the signal to an external reader antenna. This frequency division architecture resolves the conventional self-interference issue in radio frequency ID sensors by separating the received and transmitted frequencies. The detection of oil and epoxy is successfully demonstrated.