In this study, we provided a comprehensive methodology for designing and integrating miniature system in the biosensor application. In general, the network analyzer is commonly used for acoustic wave sensor measurement. However, it is remarkably inconvenient for portable use. Therefore, we presented a readout concept, which was focused on the miniaturization of the flexural plate wave (FPW) sensor system by integrating phase detection circuit. The miniature system includes a Wien-Bridge oscillator, a voltage following, a FPW device, a phase-locked loop, a phase detector, a MCU, and a LCM display. This work succeeded in integrating all the subsystems. And the core technology of the system is the phase detection function. The results showed the phase shift resolution is 10 mV/1°.