Patent ID: 7266159

Claim:
A method for reducing spurious emissions in an amplified non-baseband signal, comprising the steps of: (a) receiving a non-baseband input signal; and (b) applying pre-distortion to the non-baseband input signal to generate a pre-distorted non-baseband signal, such that, when the pre-distorted non-baseband signal is applied to an amplifier to generate the amplified non-baseband signal, the pre-distortion reduces the spurious emissions in the amplified non-baseband signal, wherein step (b) comprises the steps of: (1) generating a main non-baseband pre-distortion signal from the non-baseband input signal; (2) generating a secondary non-baseband pre-distortion signal, whose magnitude and phase are frequency-dependent, from the non-baseband input signal; and (3) combining the main non-baseband pre-distortion signal and the secondary non-baseband pre-distortion signal to generate the pre-distorted non-baseband signal, wherein the secondary non-baseband pre-distortion signal has: a magnitude proportional to a frequency offset from a carrier frequency of the non-baseband input signal; a phase shift of +90 degrees on one side of the carrier frequency; and a phase shift of −90 degrees on the other side of the carrier frequency.