Ultrasonic sensor with reverberant vibration suppression circuit

An ultrasonic sensor comprising:

• an oscillator including a drive electrode to which an excitation signal that causes a vibrating body to vibrate is applied and a detection electrode that extracts a detection signal corresponding to vibration of the vibrating body, and the oscillator being configured to emit an ultrasonic wave;
• a transmission circuit configured to output the excitation signal that causes the vibrating body to vibrate to the drive electrode;
• a reception circuit configured to receive the detection signal detected by the detection electrode;
• a reverberant vibration suppression circuit configured to, after the output of the excitation signal from the transmission circuit to the drive electrode is stopped, amplify a reverberant vibration suppression circuit control signal corresponding to reverberant vibration of the vibrating body output from the reception circuit to generate and supply a suppression control signal that reduces or prevents the reverberant vibration to the drive electrode, and including a band variable calculation amplifier having a variable frequency band of signal amplification without changing a gain of signal amplification in a low frequency range below a cutoff frequency compared to in a high frequency range above the cutoff frequency;
• and
• a control circuit configured to, after output of the suppression control signal from the reverberant vibration suppression circuit to the drive electrode is stopped, vary the variable frequency band of signal amplification of the band variable calculation amplifier.