Method and apparatus for quadrature modulation

摘要

A quadrature modulator which compensates for phase errors introduced by the quadrature oscillator is described. The principle underlying the phase error compensation is the well known fact that when two vectors of equal magnitude and arbitrary phase difference are combined to form a sum vector and a difference vector, the sum vector and the difference vector are guaranteed to differ in phase by exactly 90 degrees. Any resulting magnitude errors are taken care of by appropriately scaling I and Q signals before calculating sum and difference. The scaling factors depend on the phase error of the quadrature oscillator. <IMAGE>