RF MEMS压控振荡器及相位噪声特性的研究

RF MEMS压控振荡器及相位噪声特性的研究

利用RF MEMS 可变电容作为频率调节元件,制备了中心频率为2 GHz 的MEMS VCO 器件. RF MEMS 可变电容采用凹型结构,其控制极板与电容极板分离,并采用表面微机械工艺制造,在2 GHz 时的Q 值最高约为38. 462. MEMS VCO的测试结果表明,偏离2. 007 GHz 的载波频率100kHz 处的单边带相位噪声为- 107 dBc/ Hz ,此相位噪声性能优于他们与90年代末国外同频率器件. 并与采用GaAs 超突变结变容二极管的VCO 器件进行了比较,说明由于集成了RF MEMS 可变电容,使得在RF MEMS 可变电容的机械谐振频率近端时,MEMS VCO 的相位噪声特性发生了改变.

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 .