Solutions for optimizing a bulk bias across a substrate of an ETSOI device are disclosed. In one embodiment, an apparatus for optimizing a bulk bias across a substrate of an ETSOI device is disclosed, including: a sensing circuit for sensing at least one predetermined circuit parameter; a charging circuit for applying a bias voltage to the substrate of the ETSOI device; and a processing circuit connected to the sensing circuit and the charging circuit, the processing circuit configured to receive an output of the sensing circuit, and adjust the bias voltage applied to substrate of the ETSOI device in response to determining whether the bias voltage deviates from a target amount.