US 7,248,642 B1 · Frequency-dependent phase pre-distortion for reducing spurious emissions in communication networks

Abstract

A frequency-dependent phase pre-distortion technique is applied to an input signal in order to reduce spurious emissions resulting from subsequent amplification of the signal. In preferred embodiments, the frequency-dependent phase pre-distortion of the present invention is implemented in combination with the (frequency-independent) magnitude and phase pre-distortion technique described in U.S. patent application Ser. No. 09/395,490 (“the '490 application”), where one or more frequency-dependent phase pre-distortion signals are either advanced or delayed relative to the main pre-distorted signal generated in accordance with the '490 application. Each frequency-dependent phase pre-distortion signal is preferably based on a 180° phase difference between a pair of (critical) frequencies located outside (e.g., one on each side) of the signal channel. The magnitude of the frequency difference between the pair of critical frequencies dictates the magnitude of the desired advancement or delay in time of the frequency-dependent pre-distortion signal relative to the main pre-distorted signal. Embodiments of the present invention may be implemented in either the baseband domain or the RF domain. Implementations may also be based on look-up tables that are adaptively updated to ensure optimal performance over time.

Claims31

Dependent claims

A method for reducing spurious emissions in an amplified signal, comprising the steps of:

(a) receiving an input signal;
and
(b) applying frequency-dependent phase pre-distortion to the input signal to generate a pre-distorted output signal, wherein the frequency-dependent phase pre-distortion is based on at least one corresponding phase difference between at least one pair of critical frequencies, such that, when the pre-distorted output signal is applied to an amplifier to generate the amplified signal, the frequency-dependent phase pre-distortion reduces spurious emissions in the amplified signal, wherein step (b) comprises the steps of:
(1) generating a main output signal from the input signal;
(2) generating one or more frequency-dependent phase pre-distortion signals from the input signal;
and
(3) advancing or delaying each frequency-dependent phase pre-distortion signal relative to the main output signal;
and
(4) combining each advanced or delayed frequency-dependent phase pre-distortion signal with the main output signal to generate the pre-distorted output signal.

6 more elements

Dependencies are inferred from the claim text.

Frequency-dependent phase pre-distortion for reducing spurious emissions in communication networks

Life of this patent

Frequency-dependent phase pre-distortion for reducing spurious emissions in communication networks

Life of this patent

Abstract

Claims31