The present disclosure relates to a system for biasing a power amplifier. The system can include a first die that includes a power amplifier circuit and a passive component having an electrical property that depends on one or more conditions of the first die. Further, the system can include a second die including a bias signal generating circuit that is configured to generate a bias signal based at least in part on measurement of the electrical property of the passive component of the first die.

A novel and useful adaptive antenna tuner and associated calibration mechanism for passive adaptive antenna matching networks. The tuner is suitable for use with cellular antennas and in one embodiment uses MEMS based tunable devices. The tuner contains voltage and current sensors inserted before the antenna matching network. The sensed complex impedance generates one or more update control signals for the tuning algorithm which drives the MEMS-based tunable devices.

A power amplifier includes an input for receiving an RF signal to be amplified; at least one power amplification circuit module in electrical connection with the input for amplifying the RF signal; at least one biasing circuit in electrical connection with the power amplification circuit for compensating the distortion of the RF signal so as to amplify the RF signal substantially linearly, and an output arranged to output the amplified RF signal.

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.

Provided is a power amplification module that includes: an amplification transistor that has a constant power supply voltage supplied to a collector thereof, a bias current supplied to a base thereof and that amplifies an input signal input to the base thereof and outputs an amplified signal from the collector thereof; a first current source that outputs a first current that corresponds to a level control voltage that is for controlling a signal level of the amplified signal; and a bias transistor that has the first current supplied to a collector thereof, a bias control voltage connected to a base thereof and that outputs the bias current from an emitter thereof.

Provided is a power amplification module that includes: a first amplification circuit that amplifies a first signal and outputs the amplified first signal as a second signal; a second amplification circuit that amplifies the second signal and outputs the amplified second signal as a third signal; and a feedback circuit that re-inputs/feeds back the second signal outputted from the first amplification circuit to the first amplification circuit as the first signal. The operation of the first amplification circuit is halted and the first signal passes through the feedback circuit and is outputted as the second signal at the time of a low power output mode.

A transmission module includes an amplifier that amplifies a plurality of transmission signals in different frequency bands, a power supply voltage regulator circuit that supplies different power supply voltages for the respective frequency bands of the transmission signals to the amplifier, and a variable matching circuit including at least one variable capacitor element and at least one fixed inductor element. The variable matching circuit satisfies different output impedance matching conditions of the amplifier for the respective frequency bands of the transmission signals by changing a capacitance value of the at least one variable capacitor element on the basis of a change in the output impedance matching conditions of the amplifier in response to a change in the power supply voltages supplied to the amplifier.

Various methods and circuital arrangements for protection of a power amplifier from over voltage are presented. According to one aspect, a protection circuit coupled to a varying supply voltage of the power amplifier controls a biasing current to the power amplifier to limit a power dissipation through the power amplifier. An overvoltage protection circuit detects a level of the varying supply voltage and decreases the biasing current as a linear function of an increasing supply voltage once the supply voltage reaches a programmable voltage level. A slope of the linear function can be made programmable. Programmability of the voltage level and the slope can be used to control biasing currents to a plurality of power amplifiers operating at different times and having different requirements in terms of voltage limits and thermal breakdown. According to another aspect a voltage to current converter for use in the overvoltage protection circuit is presented.

An outphasing amplifier includes first to fourth amplifiers, first and second impedance converters, a first matching circuit, a second matching circuit, a third matching circuit matching output impedance of first impedance converter with input impedance of third amplifier, a fourth matching circuit matching output impedance of second impedance converter with input impedance of fourth amplifier, and a combiner combining the first signal amplified by third amplifier and the second signal amplified by fourth amplifier, wherein a first phase difference of the first signal input to third matching circuit with respect to the first signal output from first matching circuit is less than 90? at a center frequency of an operating frequency band, and a second phase difference of the second signal input to fourth matching circuit with respect to the second signal output from second matching circuit is more than 90? at the center frequency.

An amplifier may include first and second terminals to receive first and second input signals and a differential amplifier providing differential amplification of the first and second input signals. The differential amplifier may include a first differential amplifier stage to receive the first input signal and a second differential amplifier stage to receive the second input signal. The amplifier may further include a first bias circuit to bias the first differential amplifier stage, where the first bias circuit is connected to the second input terminal to provide anti-phase bias control of the first differential amplifier stage. The amplifier may further include a second bias circuit to bias the second differential amplifier stage, where the second bias circuit is connected to the first input terminal to provide anti-phase bias control of the second differential amplifier stage.