In a case where the power of a signal to be amplified is greater than or equal to a threshold value, a signal distributor (2) outputs one of signals to a carrier amplifier (6), outputs another signal, a phase of which is 90 degrees behind that of the one of the signals, to a peak amplifier (8), and adjusts a phase shift amount of a signal shifted by a phase shifter (7) depending on the frequency of the signal to be amplified. In a case where the power of the signal to be amplified is less than the threshold value, the signal distributor (2) outputs the one of the signals to the carrier amplifier (6) without outputting the other signal to the peak amplifier (8).

A power amplifier (PA) system is provided for multi-mode multi-band operations. The PA system includes one or more amplifying modules, each amplifying module including one or more banks, each bank comprising one or more transistors; and a plurality of matching modules, each matching module being configured to be adjusted to provide impedances corresponding to frequency bands and conditions. A controller dynamically controls an input terminal of each bank and adjusts the matching modules to provide a signal path to meet specifications on properties associated with signals during each time interval.

A low-noise amplifier system is disclosed. The low-noise amplifier system includes a low-noise amplifier having an input node and an output node in a receive path and a capacitance equalization network coupled to the output node. Compensation capacitance of the capacitance equalization network sums with non-linear capacitance of the low-noise amplifier such that a total capacitance at the output node varies by no more than 5% over an output voltage range within voltage headroom limits of the low-noise amplifier for a given supply voltage of the low-noise amplifier. In at least some exemplary embodiments, the compensation capacitance of the capacitance equalization network is a function of output signal voltage at the output node.

An amplifier system including a push-pull power amplifier having an input to receive a radio frequency (RF) input signal and an output, the push-pull power amplifier being configured to amplify the RF input signal and provide at the output an RF output signal that is an amplified version of the RF input signal, a switchable shunt capacitance switchably connected between a load-line connected to the output of the push-pull power amplifier and a reference potential, and a switch configured to selectively connect the switchable shunt capacitance to the reference potential and disconnect the switchable shunt capacitance from the reference potential to vary an impedance of load-line.

A tunable amplifier includes continuous tunability for both frequency and power levels. The tunable amplifier includes a combination of a tunable series resonator and a multi-stage LC network as the output matching network. The tunable amplifier incorporates a variable diode varactor with high breakdown voltage and high tuning range into a tunable resonator. The tunable resonator is connected to a fixed output matching network to enable a wide range of operating frequencies. The tunable amplifier enables high power, high efficiency, broadband and load-modulated power amplification, which is greatly desired for next-generation wireless communication systems and other high-frequency applications.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

An improved architecture for a radio frequency (RF) power amplifier, impedance matching network, and selector switch. One aspect of embodiments of the invention is splitting the functionality of a final stage impedance matching network (IMN) into two parts, comprising a base set of off-chip IMN components and an on-chip IMN tuning component. The on-chip IMN tuning component may be a digitally tunable capacitor (DTC). In one embodiment, an integrated circuit having a power amplifier, an on-chip IMN tuner, and a selector switch is configured to be coupled to an off-chip set of IMN components. In another embodiment, an integrated circuit having an on-chip IMN tuner and a selector switch is configured to be coupled through an off-chip set of IMN components to a separate integrated circuit having an RF power amplifier.

A radio-frequency (RF) transceiver front-end circuit includes an antenna, a power amplifier, a low-noise amplifier, a first switch unit and a second switch unit. The power amplifier is connected to a transmitting unit and the antenna to form a transmission path. The low-noise amplifier is connected to a receiving unit and the antenna to form a reception path. The transmission path and the reception path selectively do not include a /4 transmission line connected to the antenna. The RF transceiver front-end circuit has a receiving state and a transmitting state. In the receiving state, the first switch unit is controlled and causes the transmission path to have high impedance. In the transmitting state, the second switch unit is controlled and causes the reception path to have high impedance.

A polar transmitter includes an amplitude path comprising an amplitude signal that corresponds to an amplitude of a vector sum of an in-phase input signal and a quadrature input signal; a phase path comprising a phase modulator configured to phase-modulate a phase signal that corresponds to the phase of the vector sum of the in-phase input signal and the quadrature input signal; a digital power amplifier (DPA) configured to amplify the phase-modulated (PM) input signal based on the amplitude signal; a tunable matching network coupled to an output of the DPA and configured to adjust a load impedance of the DPA; and a controller configured to adjust the matching network based on a look-up table with respect to amplitude and frequency information, where the look-up table indicates a plurality of optimal operation modes of the matching network for specific combinations of amplitude and frequency information.

An amplification circuit configured to generate an output signal by differentially amplifying first and second input signals. The first and second input signals are a differential signal pair. Alternatively, the first input signal is a single-ended signal, and the second input signal is a reference signal. The amplification circuit is configured to perform a differential amplification operation by increasing a gain for generating an output signal based on the first input signal.