The exciting of vibronic oscillatory systems, composed of an oscillatable unit and a electromechanical transducer unit, occurs, most often, by means of an analog oscillatory circuit. The oscillatory circuit provokes oscillation with the frequency, at which the phase shift between transmission signal and received signal of the electromechanical transducer unit fulfills the oscillatory circuit condition, i.e., together with the remaining phases arising in the oscillatory circuit, a natural multiple of 360° results. The analog electronic components of such an oscillatory circuit are matched specially to the particular oscillatory system, e.g. to an oscillatory fork with a certain geometry, so that one oscillatory system is not easily replaceable by another, without replacing the oscillatory circuit with one correspondingly matched.
Likewise known are methods, in the case of which the oscillatory system is excited by means of a so-called PLL (phase locked loop) to execute oscillations at a certain phase relationship. This control loop can be embodied with analog parts or partially or completely digitally. A digital PLL has the advantage that it is adaptable to other oscillatory systems. Disadvantageous, however, is that, for exciting by means of a digital PLL, an increased electrical current consumption is needed, since the hardware resources must be driven.