Dynamic RF amplifier bias control for digital wireless communications devices
US6535066B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 21, 2001 |
| Grant date | Mar 18, 2003 |
| Priority date | — |
| Expiry date | Jun 21, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2201/3203
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.