A 40-nm CMOS Complex Permittivity Sensing Pixel for Material Characterization at Microwave Frequencies

A 40-nm CMOS Complex Permittivity Sensing Pixel for Material Characterization at Microwave Frequencies

Vlachogiannakis, G. (TU Delft Electronics)
Pertijs, M.A.P. (TU Delft Electronic Instrumentation)
Spirito, M. (TU Delft Electronics)
de Vreede, L.C.N. (TU Delft Electronics)

2018

A compact sensing pixel for the determination of the localized complex permittivity at microwave frequencies is proposed. Implemented in the 40-nm CMOS, the architecture comprises a square patch, interfaced to the material-under-test sample, that provides permittivity-dependent admittance. The patch admittance is read out by embedding the patch in a double-balanced, RF-driven Wheatstone bridge. The bridge is cascaded by a linear, low-intermediate frequency switching downconversion mixer, and is driven by a square wave that allows simultaneous characterization of multiple harmonics, thus increasing measurement speed and extending the frequency range of operation. In order to allow complex permittivity measurement, a calibration procedure has been developed for the sensor. Measurement results of liquids show good agreement with theoretical values, and the measured relative permittivity resolution is better than 0.3 over a 0.1-10-GHz range. The proposed implementation features a measurement speed of 1 ms and occupies an active area of 0.15x0.3 mm², allowing for future compact arrays of multiple sensors that facilitate 2-D dielectric imaging based on permittivity contrast.

Biomedical sensors
bridge circuits
complex permittivity measurement
integrated microwave circuits
micro-wave sensors

http://resolver.tudelft.nl/uuid:0861cad0-5f57-48a7-bfe7-56a5f77cfed6

https://doi.org/10.1109/tmtt.2017.2753228

0018-9480

IEEE Transactions on Microwave Theory and Techniques, 66 (3), 1619-1634

Accepted Author Manuscript

Institutional Repository

journal article

© 2018 G. Vlachogiannakis, M.A.P. Pertijs, M. Spirito, L.C.N. de Vreede