Drive circuit

A drive circuit comprising:

• an AC signal source circuit configured to generate AC signal;
• a control circuit configured to control the AC signal source circuit to provide a first AC signal and a second AC signal;
• a reference voltage generation circuit configured to supply a first drive signal having a constant amplitude AC voltage, based on the first AC signal to a first node of an external load element;
• a voltage-to-current conversion circuit configured to supply a second drive signal having a constant amplitude AC current, based on the second AC signal to a second node of the external load element;
• and
• a comparator circuit configured to be connected with the first node and the second node of the external load element, and configured to output an output voltage based on a voltage comparison result of the first drive signal supplied from the first node and the second drive signal supplied from the second node,
• wherein the control circuit is further configured to adjust a phase of the second AC signal to be reverse phase with respect to the first AC signal, based on the output voltage from the comparator circuit.