| 摘要 |
<p>Pre-distortion, whose magnitude - and preferably phase - are frequency-dependent, is applied to a non-baseband input signal in order to reduce spurious emissions resulting from subsequent amplification of the signal. In preferred embodiments, the pre-distortion technique of the present invention is implemented in combination with the (frequency-independent) magnitude and phase pre-distortion technique described in U.S. Patent Application No. 09/395,490 ('the '490 application'), where the frequency-dependent pre-distortion corresponds to amplifier distortion that has a magnitude that is proportional to the frequency offset from the carrier frequency and a phase shift of 90° on either side of the carrier frequency. Since these characteristics match those of a differentiator, a thorough correction of this part of the amplifier's distortion can be achieved using a differentiating circuit. Embodiments of the present invention may be implemented in the RF domain. Implementations may also be based on look-up tables that are adaptively updated to ensure optimal performance over time.</p> |
