Generator and operation method thereof

An operation method of a generator, the method comprising:

• supplying, by a drive circuit of the generator, a power to an ultrasonic transducer, the drive circuit being connected to a surgical instrument including a vibration system having a probe and the ultrasonic transducer;
• detecting, by at least one control circuit, a first trigger that is generated in response to the probe contacting a living tissue, the first trigger causing the at least one control circuit to perform a resonance-point search on the vibration system;
• upon detecting the first trigger, determining, by the at least one control circuit, a resonance point of a frequency of vibration of the probe by performing the resonance-point search on the vibration system;
• upon determining the resonance point, causing, by the at least one control circuit, the drive circuit to execute a standby operation by supplying power to the ultrasonic transducer so as to maintain resonance of the frequency based on the determined resonance point;
• detecting, by the at least one control circuit, a second trigger causing the surgical instrument to treat the living tissue;
• and
• upon detecting the second trigger, causing, by the at least one control circuit, the drive circuit to execute an actual output operation by increasing the supply of power to the surgical instrument such that the surgical instrument treats the living tissue.