Patent ID: 7944989

Claim:
A quadrature modulation apparatus, comprising: an in-phase correction signal outputter that generates an in-phase correction user signal by adding an in-phase user signal to an in-phase correction signal of a sinusoidal voltage; an in-phase signal outputter that generates an in-phase offset user signal by adding an in-phase voltage signal to the in-phase correction user signal; an in-phase signal converter that outputs an in-phase conversion signal by mixing an in-phase local signal of a predetermined local frequency with the in-phase offset user signal; a quadrature correction signal outputter that generates a quadrature correction user signal by adding a quadrature user signal to a quadrature correction signal, which is different in phase by approximately 90 degrees from the in-phase correction signal; a quadrature signal outputter that generates a quadrature offset user signal by adding a quadrature voltage signal to the quadrature correction user signal; a quadrature signal converter that outputs a quadrature conversion signal by mixing a quadrature local signal, which is different in phase by approximately 90 degrees from the in-phase local signal, with the quadrature offset user signal; an adder that adds the in-phase conversion signal to the quadrature conversion signal; an output voltage measurer that measures an output voltage of said adder; and an error determiner that determines an error of the quadrature modulation based upon a measurement result of said output voltage measurer.