Q-Loading of Colpitts-Based Mass-Sensing Oscillators in Resonator-based MEMS Airborne Particulate Matter (PM) Sensors

Air pollution is a major world-wide health concern, in particular the adverse effects resulting of exposure to fine airborne particulate matter (PM 2.5 ). Oscilator topologies have thus far been an overlooked aspect of MEMS based gravimetric PM-sensors. In this work, we analyze the effect of mass loading on selected Colpitts oscillator topologies. Five different Colpitts oscillators are considered in this paper, single ended and differential versions of common gate and common drain and an inverter-based Colpitts oscillator. Our results show that the Complementary common gate topology is the most stable regarding change in frequency and amplitude. The frequency of the complementary common gate increases by 2.5% to 114MHz when the loading is increased to 3KΩ and 11%. with a loading of 6KΩ.