According to embodiments of the present invention, an oscillator is provided. The oscillator includes a switched capacitor circuit arrangement configured to generate a predetermined voltage, a transconductance-capacitor filter configured to receive the predetermined voltage and a reference voltage, and to generate an output filter voltage based on a differential result between the predetermined voltage and the reference voltage, wherein a value of the output filter voltage is variable in response to the differential result, and a period control circuit arrangement configured to receive the output filter voltage, and further configured to generate an oscillator signal, wherein a period of the oscillator signal is variable in response to the value of the output filter voltage, wherein the oscillator is configured to control the switched capacitor circuit arrangement based on the oscillator signal to generate the predetermined voltage to be matched to the reference voltage.