A precision current reference or a precision oscillator includes a circuit that precisely controls the cyclic charging of a switched capacitor. The voltage across the switched capacitor is ramped up to a desired voltage during the charge phase. The circuit comprises a network of switched capacitors around a transconductance amplifier. An error voltage between a predetermined voltage and a voltage across the switched capacitor is amplified by a transconductance amplifier to give an error current, which is integrated over time to give an integrated error voltage. The error voltage can be minimized such that the circuit produces a precise output current whose value depends on the switched capacitor capacitance, the predetermined reference voltage and a frequency used to switch the switched capacitors. Alternatively, an embodiment may be part of a frequency locked loop to provide a precise oscillator whose frequency depends on a predetermined resistance and the switched capacitor capacitance.