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:
Dec. 25, 2007
Filed:
Dec. 20, 2005
William J. Roeckner, Carpentersville, IL (US);
Pallab Midya, Palatine, IL (US);
Patrick L. Rakers, Kildeer, IL (US);
Lawrence E. Connell, Naperville, IL (US);
Daniel A. Mavencamp, Dallas, TX (US);
Bradley C. Stewart, Phoenix, AZ (US);
William J. Roeckner, Carpentersville, IL (US);
Pallab Midya, Palatine, IL (US);
Patrick L. Rakers, Kildeer, IL (US);
Lawrence E. Connell, Naperville, IL (US);
Daniel A. Mavencamp, Dallas, TX (US);
Bradley C. Stewart, Phoenix, AZ (US);
Freescale Semiconductor, Inc., Austin, TX (US);
Abstract
A closed loop audio amplifier system and method of powering up/down the system without producing audible artifacts are provided. During power up, a prebias voltage is provided to each output connected to a speaker to increase the voltage to a nominal output level. High impedance switches are then driven at a 50% duty cycle. Feedback from the output is supplied to a servo, which is enabled to fine tune the output voltage. Low impedance switches are then driven at a 50% duty cycle at a quarter cycle timing. The order of the feedback loop depends on which of the high or low impedance switches are driven. The prebias voltage is then removed before audio signals to be amplified are supplied to the system. Timing of driving of the switches is programmable. To power down, essentially the reverse sequence is provided.