An apparatus for determining and/or monitoring at least one process variable of a medium. The apparatus includes: at least one mechanically oscillatable unit; at least one transducer unit, which excites the mechanically oscillatable unit to mechanical oscillations based on an exciter signal and which receives the mechanical oscillations of the mechanically oscillatable unit and converts such to a received signal. The transducer unit has at least one piezoelectric element. The apparatus further includes: at least one electronics unit, which supplies the transducer unit with the exciter signal and which receives the received signal from the transducer unit; and at least one compensation element, which supplies the exciter signal to the electronics unit and from which the electronics unit receives a compensation signal. The invention provides that the compensation element has at least one at least element made at least partially of a piezoelectric material.