High-Performance Micromachined Inductors Tunable by Lead Zirconate Titanate Actuators

This letter documents the design, microfabrication, and testing of integrated and continuously tuned radiofrequency copper (Cu) inductors with low-power large-throw lead-zirconate-titanate (PZT) actuators. The devices, with inductances in the 3-10-nil range, achieved high-quality factors, Q >; 10 (1-6 Gilz range), and tuning ratios as high as 2.6:1 at 20-V actuation with nanowatt-power consumption. This was enabled by the monolithic integration of three electroplated Cu layers (~10 μm per layer) and PZT microelectromechanical system actuators. Two tunable inductor design types, positively and negatively coupled designs, and the tradeoff between tuning ratio and inductor Q are considered.