Design of a disk-file reference-velocity generator

The IBM 3370/3375 disk-file access servomechanism uses a nonlinear transconductance function to construct a velocity-reference generator that produces a smooth continuous phase-plane trajectory. Absence of trajectory discontinuities provides the potential for a disk-file access servomechanism to have faster access times and to have less track misregistration upon arrival at the target track center. An integrated circuit implementation of the reference-velocity generator is described, and a solution is provided for the generator´s unique loop stability and bandwidth requirements.