Tunable RF MEMS-Based Frequency Dependent Power Limiter

A novel approach for Frequency Dependent Power Limiters (FDPL) is proposed. RF MEMS switches are integrated with bandpass filters to form a power limiter where the output RF power is limited to specific levels based on the frequency band. An RF MEMS-based power limiter is analyzed both theoretically and experimentally for one frequency band. The limiter attenuates the high power signal only within the bandwidth of the integrated filter. The design of the proposed power limiter is expanded to achieve power limiting for various frequency bands. The flatness of the threshold level can be set to the desired value by controlling the return loss of the filters used in the FDPL circuit. Measured results for a FDPL circuit are presented demonstrating that the limiting power level can be controlled by adjusting the dc bias of the MEMS switches.