Patent ID: 8009762
Filing Date: 2011-08-30
Classification: H04B,H04L

Abstract:
1. A method for calibrating a polar modulated radio frequency (RF) transmitter comprising: receiving an amplitude modulated (AM) supply signal based on a first AM signal; receiving a first baseband phase modulated (PM) signal; providing a second baseband PM signal based on the first AM signal, the first baseband PM signal, and AMPM calibration constants; providing a PM RF signal based on the second baseband PM signal; providing a polar modulated RF output signal based on the AM supply signal and the PM RF signal; providing nominal AMPM calibration constants for calibrating the polar modulated RF transmitter; characterizing AMPM system responses based on at least one of a group consisting of an amplitude of the polar modulated RF output signal, a phase of the polar modulated RF output signal, and a frequency distribution of the polar modulated RF output signal at different values of the first AM signal; and calculating final AMPM calibration constants based on the AMPM system responses using phase error constraints, wherein the calculating the final AMPM calibration constants further uses output RF spectrum (ORFS) constraints, wherein the AMPM calibration constants comprise polynomial coefficients used with polynomials, and the calculating the final AMPM calibration constants further comprises: feeding initial polynomial coefficients into a search grid; identifying intermediate polynomial coefficients by determining which polynomial coefficients in the search grid meet the phase error constraints and maximize ORFS margins; updating the search grid with the intermediate polynomial coefficients; and repeating the identifying step and the updating step until final polynomial coefficients are determined.