An amplitude leveling circuit includes a variable gain, linear amplifier which receives an input signal and generates an output signal corresponding to the input signal. The signals may be in differential format. A signal processor receives the output signal and determines a corresponding mean squared signal. The signal processor includes a multiplier which squares the output signal, and an averager that averages the squared signal to generate the mean squared signal. An analyzer compares the mean squared signal with a reference and generates a feedback control signal that controls the gain of the variable gain amplifier in accordance with the difference between the mean squared signal and the reference value. The gain of the variable gain amplifier is controlled so that the amplitude of the output signal is maintained at a desired amplitude level without distorting the originally input waveform shape.