An amplifier, comprising: an input node; an output node; a gain stage having a gain stage inverting input, a gain stage non-inverting input and a gain stage output; a feedback capacitor connected in a signal path between the gain stage output and the gain stage inverting input; a sampling capacitor connected between the input node and the gain stage inverting input, and a controllable impedance in parallel with the feedback capacitor, wherein the controllable impedance is operable to switch between a first impedance state in which it does not affect current flow through the feedback capacitor, and a second impedance state in which it cooperates with the feedback capacitor form a bandwidth limiting circuit.