Ultrasonic image sensor and related electronic device

A ultrasonic image sensor, wherein the ultrasonic image sensor is coupled to sinusoidal pulse signal generating circuit, the ultrasonic image sensor and the sinusoidal pulse signal generating circuit provided below a cover plate, the ultrasonic image sensor is configured to sense a surface pattern of object to be measured that makes contact with the cover plate from above the cover plat, the ultrasonic image sensor comprises:

• an upper electrode, coupled to the sinusoidal pulse signal generating circuit;
• a lower electrode array, including a first lower electrode;
• a piezoelectric layer, provided between the upper electrode and the lower electrode array, wherein the piezoelectric layer is excited by means of a sinusoidal pulse signal generated by the sinusoidal pulse signal generating circuit so as to generate ultrasonic wave, the ultrasonic wave is transmitted along the cover plate to the object to be measured and then a reflected echo is generated, and the reflected echo along the cover plate is transmitted back to the piezoelectric layer, so that the piezoelectric layer generates a receiving signal;
• and
• a detection circuit array, including a first detection circuit, coupled to the first lower electrode and configured to determine the amplitude of the receiving signal, wherein the first detection circuit comprises:
• an operational amplifier, having a positive end, a negative end and an output end, wherein the output end is configured to output a sensing result of the ultrasonic image sensor;
• a capacitor unit, coupled between the output end and the negative end of the operational amplifier;
• a reset switch, arranged in parallel with the capacitor unit;
• a first switch, coupled between a reference voltage and the first lower electrode;
• and
• a second switch, coupled between the first lower electrode and the negative end of the operational amplifier.