Abstract: A radio frequency (RF) device and a multi-band matching circuit thereof are provided. The multi-band matching circuit includes an inductance circuit, a first capacitance circuit, an inductor, and a second capacitance circuit. A first terminal of the inductance circuit is coupled to a RF signal input terminal of the multi-band matching circuit. A first terminal of the first capacitance circuit is coupled to a second terminal of the inductance circuit. A first terminal of the inductor and a first terminal of the second capacitance circuit are coupled to a second terminal of the first capacitance circuit. A second terminal of the inductor is coupled to a first reference voltage. A second terminal of the second capacitance circuit is coupled to a second reference voltage. The second capacitance circuit is controlled by a single-bit control signal to change a capacitance value of the second capacitance circuit.

Abstract: A radio frequency (RF) device and a multi-band matching circuit thereof are provided. The multi-band matching circuit includes an inductance circuit, a first capacitance circuit, an inductor, and a second capacitance circuit. A first terminal of the inductance circuit is coupled to a RF signal input terminal of the multi-band matching circuit. A first terminal of the first capacitance circuit is coupled to a second terminal of the inductance circuit. A first terminal of the inductor and a first terminal of the second capacitance circuit are coupled to a second terminal of the first capacitance circuit. A second terminal of the inductor is coupled to a first reference voltage. A second terminal of the second capacitance circuit is coupled to a second reference voltage. The second capacitance circuit is controlled by a single-bit control signal to change a capacitance value of the second capacitance circuit.

Abstract: A radio frequency (RF) switch includes a first terminal, a second terminal, a series switch circuit, a shunt switch circuit, an inductor and a reference voltage terminal. An RF signal at the first terminal. The series switch circuit is coupled to the first terminal, the second terminal, and the shunt switch circuit. The shunt switch circuit includes a sub-switch circuit, a transistor coupled to the sub-switch circuit, and a compensation capacitor parallel-coupled to the transistor. The inductor is coupled to the shunt switch circuit and the reference voltage terminal. When the RF signal is operated in a first frequency band, the first transistor is turned on for the shunt switch circuit and the inductor to provide a first impedance. When the RF signal is operated in a second frequency band, the first transistor is turned off for the shunt switch circuit and the inductor to provide a second impedance.

Abstract: A predistorter has a first capacitor, a first bias input circuit, a second bias input circuit, a second capacitor and an impedance conversion circuit. A first end of the first capacitor is coupled to a first node of the amplifier. The impedance conversion circuit has a first resistor and a field-effect transistor (FET) and is used to perform an impedance conversion to provide a variable capacitance. A gate of the FET is coupled to an output end of the first bias input circuit, one of a source and a drain of the FET is coupled to a second end of the first capacitor and a first end of the first resistor, and another of the source and the drain of the FET is coupled to an output end of the second bias input circuit, first end of the second capacitor and a second end of the first resistor.

Abstract: A predistorter has a first capacitor, a first bias input circuit, a second bias input circuit, a second capacitor and an impedance conversion circuit. A first end of the first capacitor is coupled to a first node of the amplifier. The impedance conversion circuit has a first resistor and a field-effect transistor (FET) and is used to perform an impedance conversion to provide a variable capacitance. A gate of the FET is coupled to an output end of the first bias input circuit, one of a source and a drain of the FET is coupled to a second end of the first capacitor and a first end of the first resistor, and another of the source and the drain of the FET is coupled to an output end of the second bias input circuit, first end of the second capacitor and a second end of the first resistor.

Abstract: A predistorter has a first capacitor and an impedance conversion circuit. A first end of the first capacitor is coupled to a first node of the amplifier. The impedance conversion circuit is used to perform an impedance conversion to provide a variable capacitance. The impedance conversion circuit has a first bias input circuit and a bipolar junction transistor (BJT). The first bias input circuit is used to receive a first input bias. A base of the BJT is coupled to an output end of the first bias input circuit and a second end of the first capacitor, a collector of the BJT is floating, and an emitter of the BJT is coupled to a second node of the amplifier.

Abstract: A predistorter has a first capacitor and an impedance conversion circuit. A first end of the first capacitor is coupled to a first node of the amplifier. The impedance conversion circuit is used to perform an impedance conversion to provide a variable capacitance. The impedance conversion circuit has a first bias input circuit and a bipolar junction transistor (BJT). The first bias input circuit is used to receive a first input bias. A base of the BJT is coupled to an output end of the first bias input circuit and a second end of the first capacitor, a collector of the BJT is floating, and an emitter of the BJT is coupled to a second node of the amplifier.