An electronic component is conditioned to remove distortion in a temperature response characteristic due to a temperature hysteresis effect, by subjecting the component to a controlled temperature variation prior to operation of the component at a given temperature. A circuit is disclosed wherein the component is a zener reference element and a bias voltage of cyclical waveform and of reducing magnitude is applied to a control transistor to cause corresponding variation of the temperature of the zener via an on-chip heater. The zener is subsequently operated at a normal bias voltage corresponding to the mean value of the cyclic waveform.