From
a rigorous defect-driven point of view, it has been
demonstrated elsewhere [6] that measuring the
oscillation frequency may not be enough to achieve a
reasonable fault coverage. In general, it can be
improved drastically when taking into account the
amplitude of the oscillations, [6]. In fact, although
amplitude measurements would need additional
dedicated efforts, it was shown in [6] that the accuracy
required in the test measurements can be relaxed if
both parameters, frequency and amplitud, are
considered. Moreover, the test quality can also be
improved using additional oscillation parameters like
the distortion of the generated waves, their DC level,
etc.