Fano TDD Switch Using Crosstalk for Low-Loss Isolation

The patent extracts and eliminates the lumped capacitor component from the TDD switch design. Instead of using a discrete capacitor that requires transistor and via connections (which cause resistive losses), the invention uses the inherent parasitic capacitance between closely spaced interconnect lines. This extraction of the capacitor function to the interconnect level removes the need for additional switching components and their associated losses.

The patent introduces crosstalk between interconnect lines as an intermediary mechanism to achieve capacitance modulation. Rather than directly switching a lumped capacitor, the invention uses the electromagnetic coupling (crosstalk) between adjacent interconnects as a mediator to induce effective capacitance changes in the resonator, thereby avoiding direct transistor-via-capacitor connections and their resistive losses.

The patent extracts the switching mechanism from the traditional transistor-via-capacitor implementation and relocates it to the interconnect level. By using the presence or absence of switching activity on adjacent interconnects to modulate effective capacitance, the design achieves TDD functionality without the isolation degradation caused by imperfect transistor switches and via connections.

The patent replaces the mechanical/electrical switching system (transistors and vias) with an electromagnetic field-based system. Instead of physically connecting or disconnecting a capacitor through transistor switches, the invention uses electromagnetic crosstalk fields to induce effective capacitance changes, providing superior isolation characteristics.