Patent ID: 8081710
Filing Date: 2011-12-20
Classification: H04L

Abstract:
1. An I/Q communication transmitter, comprising: a pre-distortion lookup table containing pre-distortion lookup data comprising predetermined amplitude correction coefficients and predetermined phase correction coefficients; an auto-calibration module in communication with the pre-distortion lookup table, and configured to operate during a closed-loop auto-calibration interval, said auto-calibration module configured to calibrate the pre-distortion lookup data to compensate for a non-linearity in the I/Q communication transmitter by generating and manipulating the predistortion lookup data exclusively in polar form; a baseband processor in communication with the pre-distortion lookup table and comprising the auto-calibration module, wherein the baseband processor is configured to an I/Q modulator in communication with the baseband processor, wherein the I/Q modulator is configured to modulate an RF carrier signal based on the pre-distorted baseband I/Q signal pair and to generate a pre-distorted, modulated RF carrier signal by performing modulation operations in an I/Q domain; a power amplifier in communication with the baseband processor and the I/Q modulator, wherein the power amplifier is configured to amplify the pre-distorted, modulated RF carrier signal and to generate an amplified RF signal; a digital feedback path in communication with the power amplifier and the baseband processor, wherein the digital feedback path is configured to process the amplified RF signal to generate a polar feedback signal in a polar form and to provide the polar feedback signal to the baseband processor during the closed-loop auto-calibration interval; wherein the baseband processor is further configured to perform the following operations for updating the pre-distortion look-up data during the closed-loop auto-calibration interval: generate a polar input signal by converting the input signal from the I/Q form to a polar form; collect data regarding a nonlinear relationship between the polar feedback signal and the polar input signal; and store the data in the pre-distortion lookup table for use during the open-loop operational interval.