A CMOS ultrasound range finder microsystem

Ultrasound (US) range finders are used for contact-less distance measurements in many industrial applications. They can be used to determine liquid levels or the position of objects. The use of US for the measurement has the advantage over other methods (light) of being insensitive to dusty environment and almost independent of the object material. Existing range finders are based on piezoceramic US transducers, which tend to be bulky and expensive. For those applications where space is limited and the measurement of short distances is limited by the blind space of existing sensors, a miniaturized short range distance sensor is desirable. This fully-integrated monolithic range finder microsystem has the advantage of both size and cost, especially because the microsystem fabrication is based on a standard CMOS technology. This paper shows the schematic of the US range finder microsystem, which consists of two microtransducers (transmitter/receiver) enclosed in a dedicated sensor package.