A 5×5 Microwave Permittivity Sensor Matrix in 0.14-µm CMOS
A 0.14-µm CMOS 2-D permittivity imaging matrix prototype operating at microwave frequencies is presented. It comprises 25 permittivity-sensing pixels, each consisting of a sensing patch connected to a dedicated RF bridge. A trans-conductance stage converts the imbalance voltage to a current signal, subsequently down-converted to an intermediate frequency and sampled. The implemented sensor matrix shows precise permittivity measurements over a range of 0.1–10 GHz, and successfully demonstrates permittivity contrast with a resolution of 0.1–2.3 from 0.1 to 10 GHz when the matrix is interfaced with various dielectrics. Owing to the matrix implementation a sub-mm, permittivity discontinuity is easily resolved by the presented sensor device.