Abstract:
A method and apparatus for generating low-noise current for a disc-drive head, and in one embodiment, for a magneto-resistive head. In one embodiment, an automatic-adjustment circuit selectively disables selected pairs of current-mirror transistors to achieve a desired minimum effective width-to-length ratio of a field-effect transistor current mirror, in order to reduce device noise. In one embodiment, the current mirror provides a constant current to a magneto-resistive head in a magnetic disc drive.