Broadband Measurement of Error Vector Magnitude for Microwave Vector Signal Generators Using a Vector Network Analyzer

A frequency-domain method is proposed for the broadband measurement of Error Vector Magnitude (EVM) for Vector Signal Generators (VSGs). The technique is based on frequency-swept narrowband acquisitions performed with a Vector Network Analyzer (VNA) by exploiting a stable (yet unknown) reference signal to obtain phase-repeatable measurements, eventually allowing to refer the residual distortion contribution of the analog VSG output to its digital input. The method leverages on the formulation of a novel measurement-based model, which accounts for the IQ imbalance effect and allows to separate it from the actual distortion within the VSG, ultimately yielding accurate broadband EVM measurements at microwave carrier frequencies without any time-domain waveform reconstruction, completely avoiding the use of broadband receivers and corresponding calibration.