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.