Gerasimos Vlachogiannakis

1. Equivalent Circuit Modeling of a Single-Ended Patch Sensing Element in Integrated Technology
   Thippur Shivamurthy, H.; Z. Hu; G. Vlachogiannakis; M. Spirito; A. Neto;
   IEEE Transactions on Microwave Theory and Techniques,
   Volume 68, Issue 1, pp. 17-26, Jan. 2020. DOI: 10.1109/TMTT.2019.2956938

2. Equivalent Circuit Modeling of a Single-Ended Patch Sensing Element in Integrated Technology
   Shivamurthy, Harshitha Thippur; Hu, Zhebin; Vlachogiannakis, Gerasimos; Spirito, Marco; Neto, Andrea;
   IEEE Transactions on Microwave Theory and Techniques,
   Volume 68, Issue 1, pp. 17-26, 2020. DOI: 10.1109/TMTT.2019.2956938

3. Miniaturized Broadband Microwave Permittivity Sensing for Biomedical Applications
   G. Vlachogiannakis; Z. Hu; H. T. Shivamurthy; A. Neto; M. A. P. Pertijs; M. Spirito; L. C. N. de Vreede;
   IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology,
   Volume 3, Issue 1, pp. 48--55, March 2019. DOI: 10.1109/JERM.2018.2882564
   
   Abstract: ...

   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.

4. Miniaturized Broadband Microwave Permittivity Sensing for Biomedical Applications
   Vlachogiannakis, Gerasimos; Hu, Zhebin; Shivamurthy, Harshitha Thippur; Neto, Andrea; Pertijs, Michiel A. P.; de Vreede, Leo C. N.; Spirito, Marco;
   IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology,
   Volume 3, Issue 1, pp. 48-55, 2019. DOI: 10.1109/JERM.2018.2882564

5. Miniaturized Broadband Microwave Permittivity Sensing for Biomedical Applications
   G. Vlachogiannakis; Z. Hu; Thippur Shivamurthy, H.; A. Neto; M.A.P. Pertijs; L.C.N. de Vreede; M. Spirito;
   IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology,
   Volume 3, Issue 1, pp. 48-55, Mar. 2019. DOI: 10.1109/JERM.2018.2882564

6. A 40-nm CMOS Complex Permittivity Sensing Pixel for Material Characterization at Microwave Frequencies
   Vlachogiannakis, Gerasimos; Pertijs, Michiel A. P.; Spirito, Marco; de Vreede, Leo C. N.;
   IEEE Transactions on Microwave Theory and Techniques,
   Volume 66, Issue 3, pp. 1619-1634, 2018. DOI: 10.1109/TMTT.2017.2753228

7. A 40-nm CMOS Complex Permittivity Sensing Pixel for Material Characterization at Microwave Frequencies
   G. Vlachogiannakis; M. A. P. Pertijs; M. Spirito; L. C. N. de Vreede;
   IEEE Transactions on Microwave Theory and Techniques,
   Volume 66, Issue 3, pp. 1619-1634, March 2018. DOI: 10.1109/tmtt.2017.2753228
   
   Abstract: ...

   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.

8. A 5x5 Microwave Permittivity Sensor Matrix in 0.14-μm CMOS
   Z. Hu; G. Vlachogiannakis; M. A. P. Pertijs; L. C. N. de Vreede; M. Spirito;
   In Proc. IEEE MTT-S International Microwave Symposium (IMS),
   6 2018. DOI: 10.1109/MWSYM.2018.8439438

9. A Compact Energy Efficient CMOS Permittivity Sensor Based on Multi-Harmonic Downconversion and Tunable Impedance Bridge
   G. Vlachogiannakis; Z. Hu; H. T. Shivamurthy; A. Neto; M. A. P. Pertijs; L. C. N. de Vreede; M. Spirito;
   In Int. Microwave Biomedical Conference (IMBioC),
   pp. 1--3, June 2018. DOI: 10.1109/IMBIOC.2018.8428950
   
   Abstract: ...

   This paper presents a 0.15×0.3 mm2 complex permittivity sensor integrated in a 40-nm CMOS node. A single-ended patch, employed as a near-field sensing element, is integrated with a double-balanced, fully-differential tunable impedance bridge that is driven by a square RF pulse. The multi-harmonic, intermediate-frequency down-conversion architecture achieves a compact form factor and fast multi-frequency readout. Measurement results show good agreement with theoretical values and the measured relative permittivity variation remains below 0.3 over a 0.1-10 GHz range at a 1-ms measurement time. The energy efficiency resulting from the fast measurement time and the record-small active area allows integration in battery-operated wearables.

10. A Compact Energy Efficient CMOS Permittivity Sensor Based on Multiharmonic Downconversion and Tunable Impedance Bridge
    Vlachogiannakis, G.; Hu, Z.; Shivamurthy, H. Thippur; Neto, A.; Pertijs, M.A.P; de Vreede, L. C. N.; Spirito, M.;
    In 2018 IEEE International Microwave Biomedical Conference (IMBioC),
    pp. 1-3, 2018. DOI: 10.1109/IMBIOC.2018.8428950

11. A 5×5 Microwave Permittivity Sensor Matrix in O.14-m CMOS
    Hu, Zhebin; Vlachogiannakis, Gerasimos; Pertijs, Michiel A.P.; de Vreede, Leo; Spirito, Marco;
    In 2018 IEEE/MTT-S International Microwave Symposium - IMS,
    pp. 1160-1163, 2018. DOI: 10.1109/MWSYM.2018.8439438

12. A 40-nm CMOS permittivity sensor for chemical/biological material characterization at RF/microwave frequencies
    G. Vlachogiannakis; M. Spirito; M. A. P. Pertijs; L. C. N. de Vreede;
    In Proc. IEEE MTT-S International Microwave Symposium (IMS),
    IEEE, pp. 1‒4, May 2016. DOI: 10.1109/mwsym.2016.7540260

13. A 40-nm CMOS permittivity sensor for chemical/biological material characterization at RF/microwave frequencies
    Vlachogiannakis, Gerasimos; Spirito, Marco; Pertijs, Michiel A. P.; de Vreede, Leo C.N.;
    In 2016 IEEE MTT-S International Microwave Symposium (IMS),
    pp. 1-4, 2016. DOI: 10.1109/MWSYM.2016.7540260

14. An I/Q-mixer-steering interferometric technique for high-sensitivity measurement of extreme impedances
    G. Vlachogiannakis; H. T. Shivamurthy; M. A. D. Pino; M. Spirito;
    In 2015 IEEE MTT-S International Microwave Symposium,
    pp. 1-4, May 2015.

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