Aiming at the requirement of automatic frequency-locking of interface circuits of resonant MEMS micro-cantilever sensors

to design a phase locked loop（PLL）output amplitude of the sine wave of about 400 mV PLL circuit

and a closed loop monolithically integrated MEMS cantilever self-excitation/detection system.The PLL circuit is designed with an improved differential ring voltage-controlled oscillator structure

even if the voltage control can be realized through current regulation

and the "dead time" time-optimized phase detector

highly matched charge pump and other circuits.The overall circuit of the sensor is designed and manufactured based on the silicon on insulator（SOI）process

and the overall interface circuit completes the chip test.The phase-locked loop PLL circuit can continuously lock signals within a wide input range of 100～180 kHz to achieve accurate tracking of the sensor input signals and meet the sensor detection requirements.