Abstract: An optical drive provides an internal routine for automatically optimizing the common mode rejection ratio of the magneto-optic data output signal. A microprocessor provides control to a controller module which in turn supplies a plurality of calibration signals to a data detecting portion. The calibration signals modify predetermined parameters of the data detecting portion based upon measuring a predetermined parameter indicative of the common mode rejection ratio. The common mode rejection ratio optimization corrects for mismatches in both the optical elements and in the electronic data circuits.

Abstract: A method and apparatus are provided for biasing a non-center tapped magneto-resistive head at a constant voltage using two separate biasing stages to provide independent control over the voltage at each of the two terminals of the head. A first control device detects the voltage at a first head terminal and directs changes to the output of a current source, interconnected with a first terminal of the head, to maintain the voltage at the first terminal at a first predetermined voltage. A second control device detects the voltage at second terminal of the head and directs changes to the input of a current sink, interconnected with the second terminal, to maintain the voltage at the second terminal at a second predetermined voltage. Each control device is interconnected to a separate reference voltage source; by appropriate selection of the voltages of the reference voltage sources, the voltages at the two head terminals and the potential across the head can be established and maintained.

Abstract: An on-chip apparatus and method are provided for automatically tuning a continuous time filter in which a single filter selectively filters an information signal or, when tuning is desired, an unfiltered reference signal. During tuning, a controller determines the amplitudes of the unfiltered and filtered reference signals and their ratio. From the ratio, the controller ascertains a corresponding center or tuned frequency of the filter. If the ascertained frequency does not substantially equal a desired tuned frequency, the controller directs a bias controller to adjust the bias of the filter until the tuned frequency is substantially equal to the desired tuned frequency.