A power amplifier module includes a first current source that outputs a first current corresponding to a level control voltage for controlling a signal level of an amplified signal, a second current source that outputs a second current corresponding to the level control voltage, a first transistor in which an input signal and a first bias current are supplied to a base and an emitter is grounded, a second transistor in which an emitter is connected to a collector of the first transistor, the second current is supplied to a base, and a first amplified signal obtained by amplifying the input signal is output from a collector, and a third transistor in which the first current is supplied to a collector, a bias control current or voltage is supplied to a base, and the first bias current is supplied from an emitter to the base of the first transistor.

Embodiments disclosed herein generally relate to power amplifier matching circuits used for matching impedance and harmonic control in a device, such as a cellular phone. In one example, a power amplifier matching circuit includes two DVCs, four inductors, a transistor, and a capacitor. Utilizing the two DVCs, the impedance matching ratio and the center frequency of the circuit are capable of adjustment as needed. Moreover, the inclusion of the two DVCs may also prevent harmonic frequencies from undesirably passing through the power amplifier matching circuit to the antenna of a cellular device. The power amplifier matching circuit may be used in conjunction with an amplifier, where the output of the amplifier is proportional to the current in the circuit.

In one embodiment, an impedance matching network includes a variable reactance circuit having fixed reactance components and corresponding switching circuits. Each switching circuit includes a diode and a driver circuit. The driver circuit includes, coupled in series, a biasing current source positioned to provide a bias current to bias the diode, a first switch, a second switch, and a resistor. For each diode of each switching circuit, the control circuit is configured to receive a value related to a voltage drop on the resistor and, based on the value related to the voltage drop, adjust the bias current being provided by the biasing current source.

In one embodiment, an impedance matching network includes a variable reactance circuit having fixed reactance components and corresponding switching circuits. Each switching circuit includes a diode and a driver circuit. The driver circuit includes, coupled in series, a biasing current source positioned to provide a bias current to bias the diode, a first switch, a second switch, and a resistor. For each diode of each switching circuit, the control circuit is configured to receive a value related to a voltage drop on the resistor and, based on the value related to the voltage drop, adjust the bias current being provided by the biasing current source.

A class-F power amplifier (PA) with a matching network is disclosed herein. The class-F PA comprises a first switch and a second switch operating in differential mode, with a second harmonic trap circuitry selectively terminating the drain terminals to ground at a second harmonic frequency. The second harmonic trap circuitry comprises a plurality of lumped inductive and capacitive components. The PA further comprises a common mode trap and a matching network to reduce the imbalance of the drain terminal impedance between first harmonics and third harmonics.

A class-F power amplifier (PA) with a matching network is disclosed herein. The class-F PA comprises a first switch and a second switch operating in differential mode, with a second harmonic trap circuitry selectively terminating the drain terminals to ground at a second harmonic frequency. The second harmonic trap circuitry comprises a plurality of lumped inductive and capacitive components. The PA further comprises a common mode trap and a matching network to reduce the imbalance of the drain terminal impedance between first harmonics and third harmonics.

One aspect of the present disclosure relates to a method for operating an amplifier, the amplifier including a variable resistor coupled between a source of a first input transistor and a source of a second input transistors, and a variable capacitor coupled between the source of the first input transistor and the source of the second input transistor. The method includes adjusting a resistance of the variable resistor to adjust a low-frequency gain of the amplifier, and adjusting a capacitance of the variable capacitor in an opposite direction as the adjustment to the resistance of the variable resistor.

Improvement in linearity is achieved at low costs in a power amplifier module employing an envelope tracking system. The power amplifier module includes a first power amplifier circuit that amplifies a radio frequency signal and that outputs a first amplified signal, a second power amplifier circuit that amplifies the first amplified signal on the basis of a source voltage varying depending on amplitude of the radio frequency signal and that outputs a second amplified signal, and a matching circuit that includes first and second capacitors connected in series between the first and second power amplifier circuit and an inductor connected between a node between the first and second capacitors and a ground and that decreases a gain of the first power amplifier circuit as the source voltage of the second power amplifier circuit increases.

A transistor cell can be modeled as a transistor with a collector, a base, and an emitter operating with a current at the collector to produce a minimum transconductance in the transistor cell that increases a current gain and improves at least one operating characteristic of the transistor cell. The operating characteristics include bandwidth, gain, and output power.

A power amplification module includes: an amplifier that amplifies an input signal and outputs an amplified signal; and a harmonic-termination circuit to which harmonics of the amplified signal are input and the impedance of which is controlled in accordance with the frequency of a harmonic. The power amplification module can operate in a first mode in which a power supply voltage changes in accordance with the average voltage value of the amplified signal over a prescribed time period or in a second mode in which the power supply voltage changes in accordance with the envelope of the input signal. The impedance of the harmonic-termination circuit is controlled such that at least one even-ordered harmonic is short-circuited when the power amplification module operates in the first mode and at least one odd-ordered harmonic of third order or higher is short-circuited when the power amplification module operates in the second mode.