Novel MEMS 900 MHz electrostatic silicon delay line

We report design, fabrication and operation of a silicon acoustic delay line suitable for low voltage (1-5 V) and high-frequency (10 MHz-10 GHz) operations and implementation of signal processing and transversal filters. The acoustic waves in these delay lines were generated electrostatically using a periodic electrode that was coupled through a 1-20 nm air-gap to a slab of a poly silicon region. The propagating acoustic waves were detected using a dc-biased identical electrode array situated 0.7 cm away from the first array along the polysilicon slab. Depending on biasing conditions, our devices resonated at 301 MHz or at 903 MHz (the third harmonic).