Differential electro-mechanical oscillating circuits are described. These circuits may be used in a variety of contexts to produce differential oscillating signals, such as sine waves or square waves. A switched capacitor circuit (SCC) is used to prevent low-frequency locking, whereby the output of the resonator would otherwise lock to a constant value. More specifically, the SCC provides an impedance in parallel to the resonator between the output terminals of oscillating circuit. The SCC is designed so that, at low frequencies, its impedance is lower than the impedance of the resonator. The presence of such an impedance prevents the formation of an open circuit between the output terminals, thus maintaining the oscillating circuit in the oscillation mode. The differential electro-mechanical oscillating circuits described herein may be used to produce clock signals or otherwise to produce periodic reference signals.