Spring-Shaped Inductor Tuned with a Microelectromechanical Electrothermal Actuator

We present a spring-shaped tunable inductor, fabricated using a silicon-on-insulator (SOI) multiuser micro-electromechanical system process. The inductor has a simple planar design and is monolithically integrated in the SOI wafer. The inductor is tuned using a thermal actuator on the same silicon structure layer. Thus, the complexity and cost of fabrication are greatly minimized. The device is compact, with dimensions of 0.90 mm × 0.55 mm. In addition to cost-effective design and small surface area, the device has good tuning range and Q-factor. The experimental results show that the inductor can be tuned to 20%, 17%, and 15% at 2, 3, and 5 GHz, respectively. In air at 0 and 11.5 V, Q-factors of 7.27 and 4.64 obtained at 2 GHz, and 7.21 and 5.92 at 5 GHz. The series resonance frequency is >20 GHz.