Error vector magnitude (EVM) is a popular system-level performance metric that is defined in many communication standards, such as wireless local area networks (WLAN 802.11), mobile communications (4G LTE, 5G), and many more, as a compliance test. Beyond this, it is an extremely useful system-level metric to quantify the combined impact of all the potential impairments in a system through a single and easy to understand value.
Most RF engineers are trained on numerous RF performance parameters, such as noise figure, third-order intercept point, and signal-to-noise ratio. Understanding the combined impact of these performance parameters to the overall system-level performance can be challenging. Instead of evaluating multiple individual performance metrics, EVM offers a quick insight into the overall system. In this article, we will analyze how low level performance parameters impact the EVM and study a few practical examples to put EVM in use to optimize the system-level performance of devices. We will demonstrate how to achieve up to 15 dB lower EVM than what most communication standards target.
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