Influence of Wafer Level Packaging Modes on RF Performance of MEMS Phase Shifters

With RF MEMS technology rapid development, the distributed RF MEMS phase shifters have exhibited excellent RF performance, such as high isolation, high phase shifts, low insertion loss and wide bandwidth operation features at high frequency. However, the applications of RF MEMS phase shifter are hampered by the lack of production-worthy wafer level packaging. Therefore, the problems on packaging solved are very stringent. This paper mainly investigates on the influence of wafer level packaging modes on the RF performance of distributed RF MEMS phase shifters. The insertion loss S₂₁, return loss S₁₁ and phase shifts parameters are analyzed using 3D electromagnetic simulation tool - microwave studio (CST). Simulation results show that the insertion loss of the distributed RF MEMS phase shifters for bonding wafer packaging and wafer level micropackaging is -0.59dB and -0.061dB at l0GHz, -0.79dB and -0.25dB at 50 GHz, respectively. The return loss -11.8366dB and -26.66906dB at l0GHz, -14.50227dB and -32.30596dB at 50GHz, and the phase shift is 170.78deg and 161.82deg at 50GHz, respectively. Therefore, we concluded that different wafer level packaging modes distinctly affect the microwave performance of the distributed RF MEMS phase shifters. Comparing the RF performance parameters of two modes, the wafer level micropackaging mode shows excellent RF performance (the average insertion loss of -0.ldB and the average return loss of deg22 dB) and no resonances at 1-60 GHz, and adapted to the packaging of distributed RF MEMS phase shifters