An X-ray filter comprises an array of filter elements (5) an control circuit, the control circuit comprising an array of switching devices (33) provided on a common substrate (52), a switching device (33) being provided for each filter element for switching a control signal to the respective filter element. An output terminal of each switching device is provided with an external connection portion (54) located at the respective switching device. An array of external connection portions (54) is thus provided over the array of switching devices (33). The connection portions are then bonded to a connection block of the array of filter elements. This avoids the need to use edge connections of the substrate (52), and provides a secure mechanical and electrical connection between the control circuit and the filter array.