Ultra-low power transmit/receive ASIC for battery operated ultrasound measurement systems

AbsractThis paper describes the design of the complete transmit and receive electronics circuitry for a piezoelectric transducer in one single ASIC. The chip will be one building block in a thumb size battery operated ultrasound measurement system. The main design target has been to achieve extremely low power consumption while keeping the number of external components minimal.To overcome the dynamic range limitations imposed by a battery supply an on-chip boost converter uses one external inductor to generate up to 40 V for excitation of the transducer. The transducer itself is used as a storage capacitor, whereafter it is rapidly discharged to generate an ultrasound pulse. An on-chip amplifier with intermittent operation is controlled by a state machine and used to amplify incoming echoes. The chip has been fabricated in a 0.8 μ m high voltage CMOS process, with a total chip area of 12 mm2.Measurements verify the design approach. The power consumption for the system reaches within a factor of 2 of the power needed to charge the capacitance of the piezoelectric transducer from a fixed voltage source. The results show the possibility to achieve extremely low power consumption in a battery operated pulse–echo ultrasound measurement system.