Radio‐frequency signals may be picked up from the environment and interfere with a low‐frequency circuit. A computer‐aided method of predicting the resulting effects of this interference on the junction‐field‐effect transistors is presented in this paper. The method presented provides a convenient and simple means of analyzing the conducted‐susceptibility problem in a low‐frequency circuit. In our analysis, the parasitic components of the package are taken into account. The variation of the equivalent input‐noise voltage with the gate‐bias voltage and the decrease of the rectification factor with the increase of frequency are illustrated. The predicted results show good agreement with the experimental data.