Self-Assembling MEMS Variable and Fixed RF Inductors

Inductors play a key role in wireless front-end circuitry, yet are not generally well suited for conventional RF integrated circuit fabrication processes. We have developed inductors that can be fabricated on a conventional RFIC silicon substrate, which use warping members to assemble themselves away from the substrate to improve quality factor (Q) and self-resonance frequency (SRF), and to provide a degree of variation in inductance value. These self-assembling variable inductors are realized through foundry provided microelectromechanical systems (MEMS) processing, and have demonstrated temperature stable Q values greater than 13, SRF values well above 15 GHz, and inductance variations greater than 18%. Simulations suggest that optimized processing should yield Q values above 20 and inductance variations greater than 30%.