Fresnel-based beamforming for ultrasonic arrays

An ultrasonic beamformer for causing an ultrasonic transducer array having an array of transmitting ultrasonic elements to deliver an ultrasonic beam substantially focused at a location remote from the ultrasonic transducer array, the ultrasonic beamformer comprising:

• for each of the ultrasonic elements, an output signal line configured to carry a broadband pulse to the transmitting ultrasonic element;
• a number of pulse transmitters that is less than the number of ultrasonic elements, each pulse transmitter being configured to generate a broadband pulse different from the broadband pulse generated by each of the other pulse transmitters;
• for each of the output signal lines, a multiplexer configured to electrically connect the output signal line to the broadband pulse that is generated by a selected one of the pulse transmitters, the selected one being based on a control signal;
• and
• a multiplexer controller configured to generate the control signal for each of the multiplexers in a fashion that causes the ultrasonic beam to be substantially focused at the location remote from the ultrasonic transducer array.

An ultrasonic beamformer for substantially compensating for differences in distances between a number of ultrasonic elements in an ultrasonic transducer array and a location remote from the ultrasonic transducer array from which a reflected broadband pulse is received by each of the ultrasonic elements, the ultrasonic beamformer comprising:

• for each of the ultrasonic elements, an input signal line configured to carry the broadband pulse from the ultrasonic element;
• a number of signal shifters that is less than the number of transducer elements, each signal shifter being configured to shift the broadband pulse in a way that is different from the way the other signal shifters are configured to shift a broadband pulse, at least one of the signal shifters being a differential amplifier;
• for each of the input signal lines, a receiving multiplexer configured to electrically connect the broadband pulse received on the input signal line to a selected one of the signal shifters, the selected one being based on a control signal;
• a summer at the input of each signal shifter configured to sum the broadband pulses that are directed to the signal shifter by the multiplexers, at least one of the summers being the differential amplifier;
• and
• a multiplexer controller configured to generate the control signal for each of the multiplexers in a fashion that causes the ultrasonic beamformer to substantially compensate for the differences in the distances.