The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 17, 1998
Filed:
Apr. 30, 1996
Sassan Mortazavi, San Jose, CA (US);
Mehran Ataee, Cupertino, CA (US);
Quantum Corporation, Milpitas, CA (US);
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. A pulse width modulation (PWM) generator connected to the output control signal node generates variable duty cycle pulses related to the control level during a PWM drive mode applies the pulses to a first one of the four field effect transistors, and a polarity control circuit responds to a driving current direction signal by controlling another one of the four field effect transistors during the PWM drive mode.