Abstract: Apparatus and methods for power amplifier bias modulation for low bandwidth envelope tracking are provided herein. In certain embodiments, a power amplifier system for a mobile device includes a power amplifier that amplifies an RF signal and a low bandwidth envelope tracker that generates a power amplifier supply voltage for the power amplifier based on an envelope of the RF signal. The envelope tracking system further includes a bias modulation circuit that modulates a bias signal of the power amplifier based on a voltage level of the power amplifier supply voltage.

Abstract: The present disclosure relates to devices and methods for detecting and preventing occurrence of a saturation state in a power amplifier. A power amplifier module can include a power amplifier including a cascode transistor pair. The cascode transistor pair can include a first transistor and a second transistor. The power amplifier module can include a current comparator configured to compare a first base current of the first transistor and a second base current of the second transistor to obtain a comparison value. The power amplifier module can include a saturation controller configured to supply a reference signal to an impedance matching network based on the comparison value. The impedance matching network can be configured to modify a load impedance of a load line in electrical communication with the power amplifier based at least in part on the reference signal.

Abstract: A clamp circuit comprises a first diode stack comprising one or more diodes and an array comprising a second diode stack comprising one or more diodes and a comparator configured to compare a first voltage at the first diode stack to a second voltage at the second diode stack.

Abstract: A power amplifier comprises a first transistor, a first transformer, a first variable resistor, a first bias circuit and coupling circuitry configured to couple the first transformer, a first end of the first variable resistor, and a collector of the first transistor at a first node, the first transformer and a second end of the first variable resistor at a second node, and the bias circuit and a base of the first transistor at a third node.

Abstract: A power amplifier comprises a first transistor, a second transistor, a first emitter follower, a first bias resistor, and coupling circuitry configured to couple the first bias resistor to a base of the first transistor, the first bias resistor, the second bias resistor, and an emitter of the first emitter follower at a first node, and a base of the first emitter follower to the second transistor.

Abstract: In some embodiments, radio-frequency amplifiers can include a plurality of narrow band power amplifiers implemented. Each narrow band power amplifier can be configured to operate with a high voltage in an average power tracking mode and be capable of being coupled to an output filter associated with a respective individual frequency band. Each narrow band power amplifier can be sized smaller than a wide band power amplifier configured to operate with more than one of the frequency bands associated with the plurality of narrow band power amplifiers.

Abstract: Aspects of the disclosure include a power amplifier comprising an input to receive an input signal, an output to provide an amplified output signal, a balun coupled between the input and the output, at least one capacitor coupled to the balun, and a controllable load coupled to the at least one capacitor.

Abstract: Wideband power combiners and splitters are provided herein. In certain embodiments, a power combiner/splitter is implemented with a first coil connecting a first port and a second port, and a second coil connecting a third port and a fourth port. The first coil and the second coil are inductively coupled to one another. For example, the first coil and the second coil can be formed using adjacent conductive layers of a semiconductor chip, an integrated passive device, or a laminate. The power combiner/splitter further includes a fifth port tapping a center of the first coil and a sixth port tapping a center of the second coil. The fifth port and the sixth port serve to connect capacitors and/or other impedance to the center of the coils to thereby provide wideband operation.

Abstract: Power amplification system with adjustable common base bias. A power amplification system can include a cascode amplifier coupled to a radio-frequency input signal and coupled to a radio-frequency output. The power amplification system can further include a biasing component configured to apply one or more biasing signals to the cascode amplifier, the biasing component including a bias controller and one or more bias components. Each respective bias component may be coupled to a respective bias transistor.

Abstract: In some embodiments, an amplifier system can include an amplifier circuit having first and second amplifiers configured to amplify respective first and second portions of an input signal. Each of the first and second amplifiers can include a cascode stage with input and output transistors arranged in a cascode configuration. The amplifier system can further include an envelope tracking bias circuit coupled to the amplifier circuit and configured to provide a bias signal to the output transistor of the cascode stage of at least one of the first and second amplifiers. The amplifier system can further include a supply circuit configured to provide a non-envelope tracking supply voltage to the output transistor of the cascode stage of the at least one of the first and second amplifiers.

Abstract: One aspect of this disclosure is a power amplifier module that includes a power amplifier, a semiconductor resistor, a tantalum nitride terminated through wafer via, and a conductive layer electrically connected to the power amplifier. The semiconductor resistor can include a resistive layer that includes a same material as a layer of a bipolar transistor of the power amplifier. A portion of the conductive layer can be in the tantalum nitride terminated through wafer via. The conductive layer and the power amplifier can be on opposing sides of a semiconductor substrate. Other embodiments of the module are provided along with related methods and components thereof.

Abstract: Apparatus and methods for load modulated power amplifiers are provided. In certain embodiments, a load modulated power amplifier system includes a power amplifier that receives a radio frequency signal at an input and provides an amplified radio frequency signal at an output, and a controllable load impedance coupled to the output of the power amplifier. The controllable load impedance receives an envelope signal that changes in relation to an envelope of the radio frequency signal, and the envelope signal is operable to control an impedance of the controllable load impedance to modulate a load at the output of the power amplifier.

Abstract: Apparatus and methods for power amplifier signal limiting are disclosed. In certain embodiments, a power amplifier system includes a power amplifier that amplifies a radio frequency input signal, and a signal limiter operable to limit a signal power of the power amplifier when the radio frequency input signal exceeds a threshold. The signal limiter includes a radio frequency detector configured to generate a detection signal based on detecting a power level of the radio frequency input signal, and a latch configured to lock the signal limiter into an attenuating mode in response to the detection signal indicating that the threshold is exceeded.

Abstract: Apparatus and methods for quadrature combined Doherty amplifiers are provided herein. In certain embodiments, a separator is used to separate a radio frequency (RF) input signal into a plurality of input signal components that are amplified by a pair of Doherty amplifiers operating in quadrature. Additionally, a combiner is used to combine a plurality of output signal components generated by the pair of Doherty amplifiers, thereby generating an RF output signal exhibiting quadrature balancing.

Abstract: A power amplifier can include an input stage that includes an amplifying transistor having an input node and an output node, such that a signal at the input node has a first power level and an amplified signal at the output node has a second power level. The power amplifier can further include a bias circuit configured to provide a bias signal to the amplifying transistor, and a feedback circuit that couples the output node of the amplifying transistor to the input node of the amplifying transistor. The feedback circuit can include a resistance and a capacitance arranged in series. The power amplifier can further include a gain compensation circuit implemented relative to the input stage such that the second power level is compensated for a variation in temperature associated with the power amplifier.

Abstract: One aspect of this disclosure is a power amplifier system that includes a control interface, a power amplifier, a passive component, and a bias circuit. The power amplifier and the passive component can be on a first die. The bias circuit can be on a second die. The control interface can operate as a serial interface or as a general purpose input/output interface. The power amplifier can be controllable based at least partly on an output signal from the control interface. The bias circuit can generate a bias signal based at least partly on an indication of the electrical property of the passive component. Other embodiments of the system are provided along with related methods and components thereof.

Abstract: Apparatus and methods for power amplifier bias modulation for multi-level supply envelope tracking are provided herein. In certain embodiments, an envelope tracking system includes a power amplifier that amplifies a radio frequency signal, a multi-level supply envelope tracker that generates a power amplifier supply voltage of the power amplifier based on an envelope signal indicating an envelope of the radio frequency signal, and a bias modulation circuit that modulates a bias of the power amplifier based on a voltage level of the power amplifier supply voltage.

Abstract: Load modulated Doherty power amplifiers are provided herein. In certain embodiments, a load modulated Doherty power amplifier includes a combiner, a carrier amplifier having an output coupled to a first terminal of the combiner, a peaking amplifier having an output coupled to a second terminal of the combiner, a load modulating amplifier having an output coupled to a third terminal of the combiner, and a radio frequency (RF) output port that is coupled to a fourth terminal of the combiner and provides an RF output signal. The peaking amplifier is operable to activate at a first power threshold, while the load modulating amplifier is operable to activate at a second power threshold to modulate down a load of the carrier amplifier and of the peaking amplifier.

Abstract: In some embodiments, a power amplification system can comprise a current source, an input switch configured to alternatively feed current from the current source to a high-power circuit path and a low-power circuit path, and a band switch including a switch arm for switching between a plurality of bands. Each of the high-power circuit path and the low-power circuit path can be connected to the switch arm.

Abstract: Apparatus and methods for power amplifier bias modulation for low bandwidth envelope tracking are provided herein. In certain embodiments, a power amplifier system for a mobile device includes a power amplifier that amplifies an RF signal and a low bandwidth envelope tracker that generates a power amplifier supply voltage for the power amplifier based on an envelope of the RF signal. The envelope tracking system further includes a bias modulation circuit that modulates a bias signal of the power amplifier based on a voltage level of the power amplifier supply voltage.