A MEMS variable capacitor with high self resonance frequency

A novel configuration for a variable MEMS capacitor with D self-resonance frequency over 20 GHz, is presented. While traditional MEMS interdigital capacitor designs use two sets of fingers, the proposed MEMS capacitor uses three sets of fingers; two sets are used to construct the RF capacitor and the third set Is used for tuning. This helps in extending the self-resonance frequency and in isolating the dc bias from the RF circuit. Both Coventorware' and HFSSm simulation tools are used to optimize the capacitor performance. The capacitor was fabricated using the MetalMUMPs' process from MEMSCAP'. The achievable measured results verify the proposed concept.