An integrated circuit includes a capacitor. A switch is electrically coupled with the capacitor in a parallel fashion. A comparator includes a first input node, a second input node, and an output node. The second input node is electrically coupled with a first plate of the capacitor. The output node is electrically coupled with the switch. A transistor is electrically coupled with a second plate of the capacitor. A circuit is electrically coupled with a gate of the transistor. The circuit is configured to provide a bias voltage to the gate of the transistor so as to control a current that is supplied to charge the capacitor.