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:
Mar. 18, 2003
Filed:
Jun. 21, 2001
David Petsko, Akron, OH (US);
Cisco Technology, Inc., San Jose, CA (US);
Abstract
An adaptive bias control scheme for an Orthogonal Frequency Division Multiplex (“OFDM”) transmitter. The transmitter chain is comprised of class A amplifiers. The amplifiers in the transmit chain are backed off from P1dB to ensure linear amplification of the signal. Amplifier back off is defined as (Amplifier P1dB) minus (Average Signal Power). Since the efficiency of the amplifier decreases in direct proportion, to the back off, it is desirable to minimize back off while maintaining linearity. The back off is dependent on the peak to average power ratio (“PAPR”) of the OFDM waveform. The PAPR is measured on a symbol by symbol basis and the amplifier P1dB is adjusted in proportion to the PAPR of the symbol, maintaining a P1dB sufficient to provide the required back off dictated by the maximum PAPR of the OFDM waveform, but can be lowered for symbols with PAPR below the maximum. The average operating point of the amplifiers is reduced by the adaptive bias control on a symbol-by-symbol basis.