Iterative maps for the nonlinear Pulsed Digital Oscillator for MEMS

The Pulsed Digital Oscillator (PDO) is a sigma- delta based structure that has been proposed as a control circuit for several applications based on MEMS. A generic PDO is a sampled system that includes a MEMS resonator plus a comparator and a digital feedback loop providing the force pulses that actuate the MEMS device [2]. The most typical PDO topologies include simple and double feedback loops. This paper presents a comparison between both topologies by using the iterative maps as a new tool to analyze the nonlinearity effects on the dynamic behavior of the oscillator. To this effect, discrete-time simulation results of different PDO structures under different damping conditions are presented and analyzed.