A circuit arrangement for correcting
magneto-resistive head
asymmetry includes a shift circuit which receives a read
signal from a
magneto-resistive head, and a polarity
signal indicative of the polarity of any
asymmetry of the read
signal. Depending on the polarity of the
asymmetry, the shift circuit either adds or subtracts a shift
voltage to the read signal to produce a shifted read signal. The shift circuit outputs the read signal, the shifted read signal, and the shift
voltage. First, second and third
gain circuits are provided, which receive the read signal, the shifted read signal, and the shift
voltage, respectively, and which each receive a respective
control signal. The first, second and third
gain circuits provide respective outputs amplified proportionally based on the respective control signals. Control circuitry provides the polarity signal to the shift circuit and the respective control signals to the first, second and third
gain circuits, based on an amount of correction required. A common-mode-feedback circuit adjusts for changes in the common-mode caused by the
waveform shaping.