RF MEMS压控振荡器的研制及相位噪声特性研究

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.

Development of a RF MEMS voltage controlled oscillator and study of its phase noise characteristic

A 2GHz MEMS VCO is fabricated using a RF MEMS variable capacitor for frequency tuning. The MEMS variable capacitors with concave shape structure, whose controlling 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 phase-noise of - 107dBc/Hz at 100kHz offset from the carrier. Compared with overseas devices in the late 1990s at the same frequency, the performance of single side band (SSB) phase noise is better. And moreover, the performance of SSB phase noise is compared with VCO which is integrated with GaAs hyperabrupt junction varactor. It is explained that the characteristic of SSB phase noise changes close to the mechanical resonant frequency of RF MEMS variable capacitor.