A method, system and computer program product to control position of an error control module in a lithography apparatus using a servo control loop is described herein. The system comprises a filter, a servo controller coupled to the filter and configured to receive a control signal and an actuator coupled to the servo controller and configured to control the position of the error control module. The filter is configured to filter the control signal by modulating the amplitude and phase of the control signal in a desired frequency range, prior to the servo control loop.