Cross-correlation method measurement of error vector magnitude and application to power amplifier non-linearity performances

Error Vector Magnitude (EVM) is used by communication systems designers as one way to express distortions in digital communications. These distortions may come from initial modulator amplitude and phase imbalances, from linear distortions or non-linear distortions in the transmission chain. It is a good indicator of power amplifiers non-linearity. We propose to use a closed form method based on cross-correlation between input and output signal of the power amplifier as a way to measure either EVM or Noise Power Ratio (NPR). We show the small differences that exist between both measurements. We show also that it can be applied to the measurement of signal EVM at the output of a signal generator or transmission chain.