A radio-frequency/direct-current (RF/DC) converter is operable to receive a high-frequency and high-power RF signal and convert to a DC power. The RF/DC converter includes a first field-effect transistor (FET), a second FET, a third FET and a sixth FET that are cross-coupled. Sources of the first FET and the second FET are connected to an RF signal receiving end. Sources of the third FET and the fourth FET are connected to a potential reference end. The RF/DC converter further includes a fifth FET and a sixth FET connected subsequently to the first FET, the second FET, the third FET and the fourth.