Methods and apparatus for limiting the input voltage (swing) of a power amplifier, such as a power amplifier in a radio frequency (RF) front-end of a wireless device. One example radio frequency front-end circuit generally includes a power amplifier, a matching circuit having an output coupled to an input of the power amplifier, and an overvoltage protection circuit coupled to the matching circuit. With an overvoltage protection circuit coupled to the matching circuit in this manner, the power amplifier may have enhanced ruggedness performance.

According to one aspect, an integrated circuit having a radio frequency amplifier includes at least two amplifier stages and an impedance matching device between two amplifier stages of the radio frequency amplifier. The matching device includes two lines which are coupled by electromagnetic induction. The first line is connected to an output of the first amplifier stage and the second line is connected to an input of the second amplifier stage.

A switched capacitor modulator (SCM) includes a RF power amplifier. The RF power amplifier receives a rectified voltage and a RF drive signal and modulates an input signal in accordance with the rectified voltage to generate a RF output signal to an output terminal. A reactance in parallel with the output terminal is configured to vary in response to a control signal to vary an equivalent reactance in parallel with the output terminal. A controller generates the control signal and a commanded phase. The commanded phase controls the RF drive signal. The reactance is at least one of a capacitance or an inductance, and the capacitance or the inductance varies in accordance with the control signal.

Temperature compensation circuits and methods for adjusting one or more circuit parameters of a power amplifier (PA) to maintain approximately constant Gain versus time during pulsed operation sufficient to substantially offset self-heating of the PA. Some embodiments compensate for PA Gain “droop” due to self-heating using a Sample and Hold (S&H) circuit. The S&H circuit samples and holds an initial temperature of the PA at commencement of a pulse. Thereafter, the S&H circuit generates a continuous measurement that corresponds to the temperature of the PA during the remainder of the pulse. A Gain Control signal is generated that is a function of the difference between the initial temperature and the operating temperature of the PA as the PA self-heats for the duration of the pulse. The Gain Control signal is applied to one or more adjustable or tunable circuits within a PA to offset the Gain droop of the PA.

A radio frequency module includes a mounting board, a power amplifier, a plurality of transmission filters, a first switch, an output matching circuit, a low-noise amplifier, and an external-connection terminal. The mounting board includes a first principal surface and a second principal surface on opposite sides of the mounting board. The first switch switches a connection between the power amplifier and the transmission filters. The output matching circuit is connected between the power amplifier and the first switch. The low-noise amplifier is disposed on the second principal surface of the mounting board. The external-connection terminal is disposed on the second principal surface of the mounting board. The power amplifier, the output matching circuit, the first switch, and the transmission filters are disposed on the mounting board in stated order in a direction that is orthogonal to a thickness direction of the mounting board.

Systems and methods for amplifying a signal is described. A circuit may convert an input radio frequency (RF) signal into a first RF signal with power level matching a power capacity of a first transistor of a first size in a carrier amplifier stage, a second RF signal with power level matching a power capacity of a second transistor of the first size in a peaking amplifier stage, and a third RF signal with third power level matching a power capacity of a third transistor of a second size in another peaking amplifier stage. The circuit may amplify the first, second, and third RF signals to generate first, second, and third amplified RF signals, respectively. The circuit may combine the first, second, and third amplified RF signals, into an output RF signal that is an amplified version of the input RF signal.

A power amplifier module includes a first amplifier circuit that amplifies a radio frequency signal with a first gain corresponding to a first control signal to generate a first amplified signal; a second amplifier circuit that amplifies the first amplified signal with a second gain corresponding to a second control signal to generate a second amplified signal; and a control unit that generates the first control signal and the second control signal. The second control signal is a control signal for increasing a power-supply voltage for the second amplifier circuit as a peak-to-average power ratio of the radio frequency signal increases. The first control signal is a control signal for controlling the first gain of the first amplifier circuit so that a variation in the second gain involved in a variation in the power-supply voltage for the second amplifier circuit is compensated for.

Provided are an interstage matching circuit and a push-pull power amplifier circuit. The push-pull power amplifier circuit comprises a pre-stage push-pull amplifier circuit and a post-stage push-pull amplifier circuit. The interstage matching circuit comprises a first matching capacitor connected in series between the pre-stage push-pull amplifier circuit and the post-stage push-pull amplifier circuit; and a second matching capacitor connected in series between the pre-stage push-pull amplifier circuit and the post-stage push-pull amplifier circuit; a first matching inductor is connected with a connection node between the pre-stage push-pull amplifier circuit and the first matching capacitor, the first matching inductor is connected with a second matching inductor, the second matching inductor is connected with a connection node between the pre-stage push-pull amplifier circuit and the second matching capacitor, and a connection node between the first matching inductor and the second matching inductor is used for connecting with a feed power supply.

A multi-stage amplifier includes a first stage comprising a first common-source amplifier, a first inductive load network comprising a serial connection of a first load resistor and a first load inductor, and a first source network configured to receive a first signal and output a first load signal, and a first inter-stage inductor configured to couple the first load signal to a second signal; and a second stage comprising a second common-source amplifier, a second inductive load network comprising a serial connection of a second load resistor and a second load inductor, and a second source network configured to receive the second signal and output a second load signal, and a second inter-stage inductor configured to couple the second load signal to a third signal, wherein the first load inductor and the second load inductor are laid out to enhance an inter-stage inductive coupling.

A power amplifier module includes first and second amplifiers, a first bias circuit, and an adjusting circuit. The first amplifier amplifies a first signal. The second amplifier amplifies a second signal based on an output signal from the first amplifier. The first bias circuit supplies a bias current to the first amplifier via a current path on the basis of a bias drive signal. The adjusting circuit includes an adjusting transistor having first, second, and third terminals. A first voltage based on a power supply voltage is supplied to the first terminal. A second voltage based on the bias drive signal is supplied to the second terminal. The third terminal is connected to the current path. The adjusting circuit adjusts the bias current on the basis of the power supply voltage supplied to the first amplifier.