Abstract: A radio frequency (RF) device and its voltage generating circuit are provided. The RF device includes the voltage generating circuit and a RF circuit. The voltage generating circuit receives a RF signal and generates at least one bias voltage related to the RF signal. The RF circuit is used to receive the RF signal. The RF circuit is coupled to the voltage generating circuit to receive the bias voltage. The bias voltage is used to operate the conduction state of at least one RF transmission path of the RF circuit.

Abstract: A power amplifier device includes a first amplifier, a second amplifier, a capacitor, a node, and an impedance matching circuit. The second amplifier amplifies a radio frequency signal transmitted from the first amplifier. The capacitor is coupled between an output terminal of the first amplifier and an input terminal of the second amplifier. The node is disposed between the input terminal of the second amplifier and the capacitor. The impedance matching circuit is coupled to the node and a common voltage terminal. The impedance matching circuit is substantially an open circuit at a center frequency of the radio frequency signal. The impedance matching circuit provides substantially a short-circuited path from the node to the common voltage terminal at a frequency twice the center frequency.

Abstract: A radio frequency (RF) device and its voltage generating circuit are provided. The RF device includes the voltage generating circuit and a RF circuit. The voltage generating circuit receives a RF signal and generates at least one bias voltage related to the RF signal. The RF circuit is used to receive the RF signal. The RF circuit is coupled to the voltage generating circuit to receive the bias voltage. The bias voltage is used to operate the conduction state of at least one RF transmission path of the RF circuit.

Abstract: A power amplifier device includes a first amplifier, a second amplifier, a capacitor, a node, and an impedance matching circuit. The second amplifier amplifies a radio frequency signal transmitted from the first amplifier. The capacitor is coupled between an output terminal of the first amplifier and an input terminal of the second amplifier. The node is disposed between the input terminal of the second amplifier and the capacitor. The impedance matching circuit is coupled to the node and a common voltage terminal. The impedance matching circuit is substantially an open circuit at a center frequency of the radio frequency signal. The impedance matching circuit provides substantially a short-circuited path from the node to the common voltage terminal at a frequency twice the center frequency.