Metrology method for Error Vector Magnitude based on ellipse on IQ coordinates

The paper addresses the problems about calibration of vector modulation error, especially of Error Vector Magnitude (EVM): first, signal generator calibrates VSA and vice versa, it forms a closed-loop, so it lacks traceability. Second, signal setting of vector modulation error has always been neglected in the VSA calibration. To solve the problems, we propose new solutions to calibrate EVM, namely, by setting RF attenuation and phase shifting to construct an ellipse on IQ coordinates, get an “equivalent MPSK signals” with certain EVM. The equivalent MPSK signals' EVM are solely decided by RF attenuation and phase shifting, and thus traceable, analytically, calculable and also adjustable within a wide range. The above solutions have been proven through experiments. As a result, these solutions could be used to calibrate vector signal analyzer (VSA) and communications tester.