Microelectromechanical system cantilever-based frequency doublers

Microelectromechanical system based on-chip resonators offer great potential for high-frequency signal processing circuits such as reference oscillators and filters. This is due to their exceptional features such as small size, large frequency–quality factor product, integrability with CMOS integrated circuits, low power consumption, low-cost batch fabrication, and so on. A capacitively transduced cantilever beam resonator is one such popular microelectromechanical resonator topology. In this article, the inherent square-law nonlinearity of the voltage-to-force transfer function of a cantilever resonator’s capacitive transducer has been employed for the realization of frequency doubling effect. Using this concept, frequency doubling of input signals of 500 kHz to1 MHz and 227.5 kHz to 455 kHz have been experimentally demonstrated for two cantilever beams of length 51.75 and 76.75 µm, respectively. The microelectromechanical system cantilevers have been fabricated with polysilicon using the PolyMUMPs surface micromachining process, and their testing has been performed using laser Doppler vibrometry. The test results obtained are in reasonable compliance with the analytical and CoventorWare finite element simulation results. The high efficiency demonstrated by the cantilever frequency doubler makes it a promising choice for signal generation at high frequencies.