RF MEMS In-Line Type Phase Detector With Large Dynamic Range

An in-line type X-band phase detector is presented in this letter. It is constructed by a power combiner and a capacitive power sensor with clamped-clamped beam to obtain large dynamic range with respect to RF power. The fabrication process is based on MEMS technology. The experiments show that the return loss is smaller than -12.3 dB over X-band, the isolation is better than -9.1 dB and the insertion loss is around -3.5 dB. The conversion between phase, power, and capacitance is accomplished inside the detector for phase detection from 0 to 180°. The varying capacitance of the beam can sustain a dynamic range of 0.25 ~ 2 W with satisfactory detection sensitivity, 163.8aF/deg. at 2W. Third-order intermodulation distortion (IM3) of the detector is rather small and the IIP3 is about 37.4 dBm for 10-kHz frequency interval.