Research On VHF Band MEMS Oscillator

Timing is crucial for electronic system, and MEMS (MicroElectroMechanical Systems) technology has emerged as a very promising and competitive alternative to quartz crystal oscillator. VHF (Very High Frequency) is range from 30MHz to 300MHz,many traditional quartz crystal oscillators which are used in data computation and communication work frequency is in VHF band. It is important to do some research on VHF band MEMS oscillators to substitute for quartz crystal oscillators.In this paper, the main design proposals of electrostatic and piezoelectric resonator are analyzed. Finally, the piezoelectric resonator is selected according to the performance comparison. The piezoelectric resonator is realized by using AIN as the piezoelectric transducer material of TPoS (Thin-Film Piezoelectric-on-Substrate)structure, and the design frequency is 70MHz, 100MHz and 150MHz. Based on Piezo MUMPs process of MEMS CAPs, and with the help of L-EDIT layout software to complete the layout of the resonator,and the completion of processing by MEMS CAPs.After the processing, the bare chip was tested by the probe, and then the experiment was done at room temperature and high temperature after the package was finished, and then research on the effect of input power and temperature on resonator.Based on the MBVD (Modified Butterworth-VanDyke)model, the 100MHz resonator is modeled, and the oscillator circuit is designed and simulated in ADS. Then, the frequency stability test is carried out at room temperature. The results show that the frequency stability of MEMS oscillator is poor. Finally, The temperature compensation proposal of MEMS oscillator is studied, and the high precision temperature measurement scheme of Double-MEMS resonator structure is proposed, and the formula of temperature coefficient of multilayer material is derived.In this work, It is successful to design a VHF band MEMS oscillator, which actual operating frequency is 101.97MHz, phase noise is -110dBc/Hz@1kHz,-119dBc/Hz@10kHz, -126dBc/Hz@100kHz, -148dBc/Hz@ 1 MHz output power is 8dBm.The main work of this paper is:1. Implementing method of MEMS Resonators2. Design and Manufacture of MEMS Resonators3. Test and Modeling of MEMS Resonators4. Research on MEMS Oscillators circuit and Realization5. Research on Temperature compensation of MEMS Oscillators...