A 40-nm CMOS permittivity sensor for chemical/biological material characterization at RF/microwave frequencies

This paper presents a complex permittivity sensor, integrated in 40-nm CMOS, for microwave dielectric spectroscopy. It utilizes a single-ended patch as a near-field sensing element, embedded in a double-balanced, fully-differential impedance bridge. A low-IF, multi-harmonic down-conversion scheme is employed to extend the characterization frequency range and increase the measurement speed. The implemented architecture is compact, accurate and fast, thus suitable for the realization of future real-time, microwave-based, 2-D dielectric imagers. Measurements on liquids show an rms error of <;1% over a frequency range of 0.1 - 12 GHz.