Abstract: A memory device is provided which includes a first memory cell including a first transistor and a second transistor coupled to the first transistor in parallel. Gates of the first transistor and the second transistor are coupled to each other, and the gates of the first transistor and the second transistor pass different layers and overlap with each other. Types of the first transistor and the second transistor are the same.

Abstract: A disk drive comprises a track follow control system having a plurality of selectable frequency modes, the track follow control system configured to receive a position error signal and to output a control signal based on the position error signal, wherein the control signal is used by a head assembly to position a head over a disk. The disk drive also comprises a state estimator configured to receive the control signal and a position signal indicating a position of the head, to estimate a disturbance based on the control signal and the position signal, and to output an estimated disturbance signal based on the estimated disturbance. The disk drive further comprises a disturbance evaluator configured to receive the estimated disturbance signal, and to select one of the frequency modes of the track follow control system based on the estimated disturbance signal.