To EVM or Two EVMs?: An Answer to the Question

Error vector magnitude (EVM) is a key indicator of modulated signal quality. It measures how far a transmitted or received constellation point is from its ideal Compared to other system-level specifications such as bit error rate, the EVM contains more information about amplitude and phase distortion and circuit limitations. It is designed to be a measurement of in-band signal quality. This is one of the major reasons why EVM is widely used to quantify the degradation of modulated signals due to circuit impairments, especially for transmitters and including the effects from power amplifiers (PAs). However, there are multiple ways to calculate EVM, and these methods do not provide identical results. Therefore, it is important to be aware of these differences when a comparison with the state of the art is made. For any performance comparison to be valid, it is essential to apply the exact same metric. Otherwise, the comparison is not valid.