低电压驱动的硅基Ka波段级联式MEMS移相器

通过在共平面波导上周期性地分布微机械电容,外加电压驱动改变电容值,可实现级联式MEMS移相器.本文讨论了优化相移特性对共平面波导特性阻抗及下拉电压的要求,通过工艺参数优化制备了高阻硅基上的Ka波段级联式MEMS移相器,测试结果表明制备器件具有较低的驱动电压,8V时即产生明显的相移量,在36GHz处15V驱动电压时相移量为118°,25V时为286°.对微结构弹性膜的机械振动寿命测试表明,13级级联的MEMS移相器所有弹性膜同步振动的寿命为3×10⁶次.为器件的实用化提供了重要保障.

MEMS Distributed Phase Shifter on High-Resistivity Silicon with Low Pull-Down Voltage

The distributed phase shifters consist of a coplanar waveguide transmission line loaded periodically with MEMS capacitors,which provide variable phase shift through voltage-control of the MEMS capacitors.In this paper,the requirements of the unloaded-line impedance and pull-down voltage for the phase shifter are discussed.To improve the performance in transmission loss,the varieties of the line section where the MEMS capacitor is loaded are analyzed and calculated.The Ka-band distributed MEMS phase shifters are fabricated on the high-resistivity silicon substrate by using optimum parameters.The measured results demonstrate a low actuation voltage,producing an obvious phase shift at 8V bias,and a pull-down voltage never more than 25V.Here,a phase shift of 286°at 36 GHz is achieved.Lifetimes of 3x10⁶ cycles have been obtained for all elastic membranes as far as the phase shifter composed of 16 MEMS bridges is concerned.These offer an important guarantee for practical application of the devices.