An IDDQ test is applied to an electronic circuit (16). A power supply unit supplies power supply current to the electronic circuit. The output impedance of the power supply unit is adjusted to a value selected for the electronic circuit, the value having been selected so that a resonance circuit (14) that comprises a connection between the power supply unit and the electronic circuit is substantially critically dampened. The current sense element (18) that is used to measure IDDQ current is coupled between an external power supply and a supply input of the power supply unit, so that the current sense element does not affect the output impedance.