This paper presents a developed integrated study of the design, measurement and the application potential in phase locked loop (PLL) of a wideband MEMS phase detector. Cascaded transmission lines are adopted to realize wideband performance. Design equations are derived based on even/odd-mode analysis. Optimized structure is obtained by ANSYS simulation. The measurements focus on phase detection for large signals. The increase of the detection sensitivity tends to flatten out with the input going up to 1W. Wideband property is verified by frequency dependent measurement. Equivalent circuit modeling is proposed to study the PLL application of the phase detector. Synchronization and tracking properties are revealed.