RF MEMS壓控振蕩器及相位噪聲特性的研究

利用RF MEMS 可變電容作為頻率調節元件,制備了中心頻率為2 GHz 的MEMS VCO 器件. RF MEMS 可變電容采用凹型結構,其控制極板與電容極板分離,并采用表面微機械工藝制造,在2 GHz 時的Q 值最高約為38. 462. MEMS VCO的測試結果表明,偏離2. 007 GHz 的載波頻率100kHz 處的單邊帶相位噪聲為- 107 dBc/ Hz ,此相位噪聲性能優于他們與90年代末國外同頻率器件. 并與采用GaAs 超突變結變容二極管的VCO 器件進行了比較,說明由于集成了RF MEMS 可變電容,使得在RF MEMS 可變電容的機械諧振頻率近端時,MEMS VCO 的相位噪聲特性發生了改變.

A 2GHz MEMS VCO is fabricated using a RF MEMS variable capacitor for f requency t uning.
The MEMS variable capacitors wit h concave shape st ruct ure , whose cont rolling plates and capacitor plates are separated , are fabricated in a surface micromaching process. These devices have a quality factor of 38.462 at 2GHz. The MEMS VCO operates at 2. 007GHz , achieves a single side band p hase2noise of 2107dBc/ Hz at 100kHz off set f rom t he carrier . Compared wit h over seas devices in t he late 1990s at t he same f requency , t he performance of single side band (SSB) p hase noise is bet ter . And moreover , t he performance of SSB p hase noise is compared wit h VCO which is integrated with GaAs hyperabrupt junction varactor . It is explained that t he characteristic of SSB p hase noise changes clo se to t he mechanical resonant frequency of RF MEMS variable capacitor .