Patents by Inventor Sassan Mortazavi

Sassan Mortazavi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5838515
    Abstract: A voice coil motor (VCM) driver has four field effect transistors connected to a motor coil as an H-bridge. A sense resistor in series with the coil and the H-bridge senses coil current. A feedback amplifier provides a feedback signal from a voltage developed across the sense resistor. A summing junction sums current command signals with the feedback signal. A transconductance loop compensation amplifier has an inverting input connected to the summing junction, has a non-inverting input connected to a reference level, and has an output control signal node. The control level is connected to control linear transconductance differential driver amplifiers including the four field effect transistors during a linear drive mode.
    Type: Grant
    Filed: April 30, 1996
    Date of Patent: November 17, 1998
    Assignee: Quantum Corporation
    Inventors: Sassan Mortazavi, Mehran Ataee
  • Patent number: 5737144
    Abstract: A voltage boost circuit within a hard disk drive is realized by switching a center tap node of a three phase spindle motor to ground during a power down sequence, thereby employing inductance of the spindle motor as a voltage boost inductor. The boosted voltage is rectified and stored in a capacitor for use, e.g. to control a source transistor of an actuator driver during an actuator retract operation.
    Type: Grant
    Filed: June 5, 1996
    Date of Patent: April 7, 1998
    Assignee: Quantum Corporation
    Inventors: Mehran Ataee, Sassan Mortazavi
  • Patent number: 4849835
    Abstract: A technique and associated arrangement for detecting loss of phase/frequency lock in a phase lock loop, particularly for a magnetic disk drive servo system the phase lock loop detects timing asynchronism and loss of lock.
    Type: Grant
    Filed: March 19, 1987
    Date of Patent: July 18, 1989
    Assignee: Unisys Corporation
    Inventors: Seyed Entezarmahdi, Sassan Mortazavi