A CMOS Time Domain Microwave Broadband Dielectric Spectroscopy System with a Contact-Less Sensor for Liquid Chemical Detection

A CMOS time-domain (TD) microwave broadband dielectric spectroscopy (MBDS) system consisting of an ultra-wideband (UWB) transmitter with a broadband multi-tone excitation signal generator and a UWB DC-free direct converter receiver with the center frequency of 500 MHz along with an off-chip contact-less sensor is proposed for liquid chemical material characterization. To perform the complex permittivity detection; 1- a generated input pulse with 1 GHz bandwidth is up-converted to RF frequencies using a broadband single sideband (SSB) mixer to avoid the signal distortion at the receiver baseband, 2- the RF pulse is passed through the material-under-test (MUT) placed between two radiative near-field-coupled UWB Vivaldi antennas, and 3- phase and magnitude differences (Δφ,ΔMag) due to different MUTs are extracted from the direct down-converted signal. The 3–10 GHz MBDS system fabricated in 65nm CMOS, occupies 1.68 mm² an area and consumes ~67 mW from a 1 V supply. The proposed system is verified with four different chemical liquids, and achieves an error less than 1.2% for phase/magnitude differences over the entire operating bandwidth compared to sensor VNA measurements.