A compact ultrasonic transducer using the active piezoceramic material as electronics carrier

The integration of sensor and electronics is important to reduce size, cost and power consumption for a measurement system. Sensors based on piezoelectric ceramic materials traditionally have a low degree of sensor and electronics integration. This paper describes the design of a highly integrated ultrasound transmit/receive unit where the piezoceramic sensor is used as the carrier for the driver electronics. An optimized ASIC driver stage in bare die format and two lithium battery cells which give 6 V supply voltage are glued directly to the back side of the sensor. Electrical connections are made from the driver stage to the crystal using wire bond technology. Measurements have been performed with an air backed crystal and Plexiglas as the medium. The absence of long wiring and parasitic components between the driver stage and the driven crystal give excellent pulse control possibilities. The power consumption of the driver stage/crystal combination is linearly dependant on the repetition rate, with a current consumption of less than 20 μA at 1 kHz repetition rate. The approach taken introduces issues regarding the influence of vibrations in the MHz-range on die attachment and wire bonding connections, which need to be further investigated.Godkänd; 2004; 20060922 (ysko