What is IQ modulation?

In-phase quadrature modulation (IQ modulation) is the main modulation scheme used in communication applications. It is popular because of its efficient use of bandwidth, meeting the increasingly urgent need for bandwidth in a world where data volumes are growing exponentially. It is important to test with simulated IQ signals because designers are always faced with a lack of bandwidth in an interference-ridden spectrum.

For example, designers need to test the extreme performance of their designs so that they can ensure that they will function properly in a real environment. To do this, they must first generate an ideal signal to test the ideal performance of the design. Therefore, they must generate a known pure signal of high quality.

They can emulate non-ideal IQ signals by adjusting the gain balance between the two channels as well as the amplitude offset of each channel. They can even adjust the offset to move the I or Q baseband signal in time with picosecond resolution. Some function generators allow you to perform more advanced modulations that add noise, random jitter, or deterministic jitter to the signal.