Varactorzodilla

Varactorzodilla is a term used in semiconductor engineering to denote a hybrid electronic component that combines the voltage‑dependent capacitance characteristics of a varactor diode with the adjustable resistance function of a variable resistor. The device, first introduced in peer‑reviewed literature in 1989, is manufactured by integrating a silicon–based doped‑junction varactor with a polysilicon channel whose resistance can be tuned by an external control voltage. Unlike conventional varactors, the varactorzodilla allows simultaneous tuning of capacitance and resistance, providing a single‑shot solution for adaptive filter and oscillator design.

The varactorzodilla typically consists of a shallow p‑n junction defined on a highly doped silicon substrate surrounded by a gate electrode that modulates the depletion width. A narrow polysilicon strip running parallel to the junction functions as a variable resistor, its conductance changes with the polarity and magnitude of the gate bias. The internal structure is encapsulated in a low‑leakage oxide layer to preserve high‑frequency performance. Operation relies on the tri‑terminal control architecture: a DC voltage applied to the gate adjusts both the depletion width (altering capacitance) and the polysilicon channel resistance, enabling real‑time impedance matching.

This component has been adopted in RF integrated circuits for locally oscillated signal matching, adaptive impedance matching networks, and in tunable inductor‑capacitance (LC) filters for communication systems. Subsequent developments have focused on reducing series resistance while maintaining high Q‑factor, with notable implementations reported in the Proceedings of the IEEE and the 1995 International Electron Devices Meeting. The varactorzodilla remains primarily of academic and specialized industrial interest, with its design considerations documented in contemporary electronics handbooks and research articles.|