The ubiquity of Global System for Mobile Communications (GSM) cell phones has contributed to the steady rise in unwanted Radio Frequency (RF) signals, causing electronic circuits to give distorted results unless they possess adequate RF-noise- rejection capabilities. Consequently, RF-immunity testing has become imperative for ensuring the satisfactory operation of electronic circuits. This application note describes a general technique for measuring the RF noise-rejection capability of an integrated circuit board. RF-immunity testing subjects the board to controlled levels of RF, representing the stress likely to be encountered during its operation. The result is a standard, structured test methodology that establishes repeatable results useful in qualitative analysis. Such test results aid in the selection of integrated circuits (ICs) and circuits most resistant to RF noise.