Digital-Based Solution for the Generation of FM/PM Test Stimuli

This article explores a low-cost solution for generating modulated test stimuli using a standard digital automated test equipment (ATE). The technique relies on the generation of a modulated binary signal with appropriate encoding using a digital tester channel and the exploitation of one of its harmonic replicas. A theoretical analysis is presented in this article, considering a simple modulation scheme, i.e., the single-tone frequency or phase modulation. The relationship between the baseband spectrum and the harmonic replicas is established and an analytical expression of the modulated digital signal is derived, taking into account effects associated with discrete-time generation. A corruption estimator is then defined, enabling nondestructive sampling conditions to be identified. Experimental results are provided demonstrating the ability of the proposed solution to generate a modulated signal with the desired characteristics at a frequency higher than that of the test equipment.