| Summary: | 碩士 === 國立臺北科技大學 === 機電整合研究所 === 96 === In the study, we use 0.35μm and 0.18μm CMOS-MEMS to design the DC-contact RF switch which has the advantages of small area、easy fabrication、low -voltage and high RF performance. The switch is compatible with CMOS process. The switches are actuated by electrostatic force that drove the tail of the cantilever beam contact with the transmission line. The DC and RF signal are separated by SiO2 that avoid RF signal loss. The simulation results show that SiO2 could avoid the loss of RF signal. We also use 0.35μm CMOS-MEMS to design the contact type tunable capacitor. The switches and capacitors have similar MEMS post-process. Besides, MEMS post-process will not damage the circuit layout.
In the MEMS post-process, the device is based on aluminum as the cantilevers and the scarified layer. The structure is released by wet-etching and Supercritical CO2 drying. After MEMS post-process, we can drive the cantilever via applied voltage successfully but the switch contact part is easy to oxidize. In the situation that probes push contact part, the measurement results show. At 2.4GHz, the 0.35μm CMOS-MEMS switch Insertion Loss and Isolation are -1.99dB and -31.7dB, and the 0.18μm CMOS-MEMS switch Insertion Loss and Isolation are -5.85dB and -51.4dB, respectively. The tuning range of tunable capacitors is from 0.141pF to 0.197pF. Its variation is 33% and the quality factor is 3.65 at 2.4GHz and 0-37V.
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