A CMOS ultrasound range-finder microsystem

A miniaturized ultrasound range finder in a standard 0.8-mum CMOS technolog y is described. It uses thermally excited silicon membrane transducers to g enerate 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-cont inuous measurement requiring coherent ultrasound waves, that are delivered by an electro-mechanical phase locked loop. Circuit and system techniques a s well as package considerations are presented which allow the range finder to be implemented as a fully integrated 0.8-mum CMOS microsystem.