Electro-mechanical hybrid PLL for MEMS oscillator temperature compensation system

This paper describes the design and measurement of a dual Phase-Locked Loop system that utilizes a MEMS VCO with a DC-controlled silicon resonator as the frequency-setting element. System-level considerations are given for the use of such structure in temperature compensation system for MEMS reference oscillators. Micromachining process and circuit design challenges of the particular implementation are also discussed. The PLL has been implemented using a 0.35 μm CMOS process and operates with a nominal supply of 3 V. The nominal supply voltage for the MEMS VCO is 24 V with 15 V bias applied to the silicon resonator.