The loss mechanisms of different passive devices （on-chip inductors and capacitors） on different substrates are analyzed and compared. OPS （oxidized porous silicon） and HR （high-resistivity） substrates are used as low-loss substrates for on-chip planar LPF （low pass filter） fabrication. For the study of substrate loss, a planar coil inductor is also designed. Simulation results show that Q （the quality factor） of the inductor on both substrates is over 20. Measurements of the LPF on OPS substrate give a - 3dB bandwidth of 2.9GHz and a midband insertion loss of 0.87dB at 500MHz. The LPF on HR substrate gives a - 3dB bandwidth of 2.3GHz and a midband insertion loss of 0.42dB at 500MHz.
针对粗糙介质表面造成射频微机械(RF M EM S)开关隔离度衰减的问题,设计了一个双桥电容式RF M EM S开关,分别采用金属A u和A l作为开关的下电极,以S iN作为电容介质制备了样品。微波特性测量表明两种材料开关的隔离度有很大区别。利用原子力显微镜对金属A u和A l上制作的S iN介质层表面进行了测试,表面粗糙度R a值分别为13.050 nm和66.680 nm,分析得到相应的关态电容减少因子分别为0.52和0.15。为获得较好的开关隔离度,介质表面粗糙度须控制在5 nm以下。
