A radio frequency apparatus and a voltage generating device thereof are provided. The voltage generating device includes a first switch and a second switch. A first terminal of the first switch receives a first voltage. A control terminal of the first switch receives a second voltage. A first terminal of the second switch receives the second voltage. A control terminal of the second switch receives the first voltage. A second terminal of the second switch and a second terminal of the first switch are coupled to an output node, wherein the output node outputs an output voltage related to at least one of the first voltage and the second voltage.