A CMOS ultrasound range-finder microsystem

A miniaturized ultrasound range finder in a standard 0.8-mum CMOS technology is described. It uses thermally excited silicon membrane transducers to generate or detect ultrasound at 100 kHz and can measure distances up to 11 cm with an accuracy of 2.5 mm, The distance sensor is based on a quasi-continuous measurement requiring coherent ultrasound waves, that are delivered by an electro-mechanical phase locked loop. Circuit and system techniques as well as package considerations are presented which allow the range finder to be implemented as a fully integrated 0.8-mum CMOS microsystem.