Low energy or minimum disturbance method for measuring frequency response functions of ultrasonic surgical devices in determining optimum operating point

An ultrasonic generator configured to supply power to an ultrasonic device, the ultrasonic generator comprising:

• a drive signal generator configured to provide a drive signal;
• an amplifier having a gain configured to amplify the drive signal;
• a noise signal generator configured to provide a noise signal;
• a resonance circuit configured to provide an output to the resonator of the ultrasonic device;
• a transformer having a first primary winding coupled to the amplifier, a second primary winding coupled to the noise signal generator and a secondary winding coupled to the resonance circuit;
• and
• a controller configured to:
• receive an output signal from the ultrasonic device and the noise signal from the noise signal generator,
• calculate a transfer function estimate based on the output signal and the noise signal, and
• adjust the drive signal generator based on the calculated transfer function estimate.