Advanced Varactor Fabrication and Characterization: Paving the Way for Next-Generation Reconfigurable Antenna Systems

This paper presents a step-by-step characterization and small signal equivalent circuit model extraction of semiconductor varactor diodes. Two different device structures have been used to consolidate a primitive comparison study in terms of DC and radio-frequency characteristics. The simulation exhibited excellent agreement with the measured data, validating the model employed here. The varactor model built includes the intrinsic and extrinsic equivalent circuit parameters, ensuring that the self-resonant frequency of the device can be accurately evaluated. The varactor devices showed quality factors of 7.5 and 1.8 at 2.4 GHz signal for PN and Schottky diodes, respectively. The extracted tuning ranges of these varactors are 15 and 4.2, respectively. The downscaling of the mesa size of both devices can inevitably lead to extending their maximum operating frequencies toward the mm-wave regime.