An apparatus and method for automatically and periodically tuning a signal having a gain element, a variable impedance associated with the gain element, and a control device. The gain element has an input for receiving the signal and an output for providing an output signal and is preferably an operational amplifier with a feedback path extending from the output to the input. The variable impedance is preferably connected in series in the feedback path and includes a plurality of resistors connected in series and a plurality of switches, each switch being connected in parallel with one of the resistors. The control device receives the gain element output signal and generates a control signal in response to the amplitude of the gain element output signal. The control signal is transmitted to the variable impedance for regulating the setting of the impedance. Preferably, the control device also includes a pair of comparators for evaluating the gain element output signal and a field programmable gate array for receiving the outputs of the comparators and generating the control signal. The control signal preferably comprises a plurality of switching signals, each signal being connected to one of the switches for controlling the state of the switch.