Ultrasonic sensor and control method thereof

A method for controlling an ultrasonic sensor, the ultrasonic sensor comprising:

• a plurality of first capacitance micromachined ultrasonic transducers (CMUTs) arranged in M rows, M being an integer greater than 1, each first CMUT comprising a plurality of first electrodes, a second electrode, and a third electrode, a plurality of first cavities being formed between the first electrodes and the second electrode;
• and
• a plurality of second CMUTs arranged in N columns, N being an integer greater than 1, each second CMUT comprising a plurality of fourth electrodes, a fifth electrode, and a sixth electrode, a plurality of second cavities being formed between the fourth electrodes and the fifth electrode;
• the method comprising:
• in a transmission mode:
• applying a first reference voltage to first electrodes of first CMUTs arranged in a plurality of selected rows of the M rows;
• applying a first direct-current (DC) to second electrodes of the first CMUTs arranged in the plurality of selected rows of the M rows, the first DC voltage being different from the first reference voltage;
• and
• applying an alternating-current (AC) voltage to third electrodes of the first CMUTs arranged in the plurality of selected rows of the M rows;
• and
• in a receive mode:
• applying a second reference voltage to fourth electrodes of second CMUTs arranged in a plurality of selected columns of the N columns;
• applying a second DC voltage to fifth electrodes of the second CMUTs arranged in the plurality of selected columns of the N columns, the second DC voltage being different from the second reference voltage;
• and
• receiving alternating-current (AC) voltages generated by sixth electrodes of the second CMUTs arranged in the plurality of selected columns of the N columns.