The invention relates to a rotational speed sensor including a vibrating gyroscope which is part of a primary and a secondary control circuit. The control circuit, respectively, amplifies, demodulates, remodulates an output signal of the vibrating control circuit and supplies it again to the vibrating control circuit as an exciter signal and the primary control circuit provides most of the energy required for maintaining the vibration. A frequency synthesiser including mechanism for adjusting the phase length of the carrier is provided in order to produce carriers which are used to demodulate and remodulate. Said carrier forms, a phase control circuit in conjunction with a phase comparison circuit. The amplified output signal in the primary control circuit and a comparison carrier produced by the frequency synthesiser can be guided to the phase comparison circuit. The invention also relates to a method for equalising the inventive rotational speed sensor.