Measuring PSRR accurately

In theory, measurement of the power-supply-rejection ratio (PSRR) is relatively easy. A variable-frequency signal modulates the power-supply input, and the attenuation of that signal is measured at the output. However, the measurement is highly sensitive to setup noise, including noise from the probe-loop area and the layout of the printed circuit board (PCB). This article explores commonly encountered setup issues that limit PSRR measurement and offers a method to overcome them using high-fidelity signal injectors and a highly sensitive/selective vector network analyser (VNA).

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Originally published by Texas Instruments at www.ti.com as "Techniques for accurate PSRR measurements".