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:
Aug. 14, 2001
Filed:
Mar. 15, 2000
Clyde Washburn, Victor, NY (US);
LSI Logic Corporation, Milpitas, CA (US);
Abstract
A method and apparatus for controlling amplifier operating angle provides a corresponding increase in amplifier efficiency through a continual adjustment of operating angle from Class A, through Class AB, to Class B, an improved bandwidth in the output stage by preventing the output stage from reaching cutoff and the ability to adjust the high frequency content of the drive waveform to match that of the output stage thereby attaining the highest efficiency consistent with required distortion levels. A push-pull amplifier is coupled to a differential pushpull current drive source with out of phase drive signals and a preprocessing circuit with a first set of current sources which mirror one drive signal and a second set of current sources which mirror the other drive signal. The preprocessing circuit provides a full-wave rectified signal substantially representing the combined lower halves of the out of phase drive signals to be summed with the drive signals as composite input waveforms for the push-pull amplifier. The rectified signal is common-mode to both sides of the amplifier and gives instantaneous control of the bias point such that it is always just large enough to support the instantaneous amplitude of the signals as it adjusts the operating angle of the push-pull amplifier from Class A through Class B. A transformer is coupled to the output stages of the push-pull amplifier for summing the output signals.