Optimization of low-power oscillator topology for frequency modulated MEMS inertial sensors

摘要

This work proposes two different feedback oscillator loops for MEMS frequency-modulated (FM) inertial sensors, identifying the optimum topology in terms of power-noise trade-off. More in detail, the focus is on the critical 90-degree shifter stage, realizable through either an analog integrator or a phase-locked-loop (PLL). After a theoretical analysis, the first option turns out to minimize noise-folding related issues, obtaining lower noise level at lower power consumption with respect to the PLL approach. In order to verify the theoretical model, the two loops are fabricated and coupled with a frequency modulated accelerometer measuring the oscillator loop phase noise at the system output.