when the piezoelectric oscillating circuit has been manufactured so far this electrically conductive layer 116 a may be structured after depositing the same so that the piezoelectric oscillating circuit or several oscillating circuits manufactured on a wafer may be electrically contacted and therefore measured from the resulting impedance curve the natural frequency may then be determined depending on the frequency a second possibility is to excite the partially completed piezoelectric oscillating circuit in a different way to the electric way e g by a pulsed laser this is required when no electrically conductive layer is provided for a corresponding electrical excitement of the oscillating circuit in this case by observing the propagation of the acoustic oscillating circuit induced by the pulsed layer the natural frequency of the oscillating circuit may be determined for example from the temporal delay of the echo of the excitement of lower layers further a frequency correction may even be performed when the natural resonance of the partially completed piezoelectric oscillating circuit may not be determined by measurement in this case the natural frequency is determined by accurately measuring the layer thicknesses of all layers of the piezoelectric oscillating circuit which have been deposited up to then which however requires a very high measuring accuracy of all those layers and an accurate determination and repeatability of the acoustic parameters of all layers which were used hitherto due to the thus gained information about the layers the natural resonance may then be calculated and from this a correction may be derived after having determined the natural frequency of the piezoelectric oscillating circuit in the above.