Abstract: In accordance with some embodiments, the present disclosure relates to a dual mode control interface that can be used to provide both a radio frequency front end (RFFE) serial interface and a three-mode general purpose input/output (GPIO) interface within a single digital control interface die. In certain embodiments, the dual mode control interface, or digital control interface, can communicate with a power amplifier. Further, the dual mode control interface can be used to set the mode of the power amplifier.

Abstract: Apparatus and methods for tuning a voltage controlled oscillator (VCO) are provided. In one aspect, a method of auto-tuning in a phase-locked loop includes generating a VCO clock signal using a VCO coupled to a capacitor array, dividing the VCO clock signal to generate a divided clock signal using a prescaler circuit having a selectable division ratio, controlling a value of the selectable division ratio using a first counter and a second counter of a counter module, generating a phase-frequency detector feedback signal based on a division control signal M and the divided clock signal using the counter module, counting a number of cycles of the divided clock signal that occur during a calibration interval using a cycle counter of a digital processing logic circuit, and determining the value of a capacitor array control signal based on the number of cycles counted during the calibration interval.

Abstract: In a voltage converter, a mode configuration is selected in response to a mode control signal using a switch matrix having two or more mode configurations. Each mode configuration corresponds to one of two or more output signal voltages. The output signal is compared with a reference signal to produce a direction comparison signal. The direction comparison signal is used to produce the mode control signal.

Abstract: A power amplifier module includes a power amplifier including a GaAs bipolar transistor having a collector, a base abutting the collector, and an emitter, the collector having a doping concentration of at least about 3×1016 cm?3 at a junction with the base, the collector also having at least a first grading in which doping concentration increases away from the base; and an RF transmission line driven by the power amplifier, the RF transmission line including a conductive layer and finish plating on the conductive layer, the finish plating including a gold layer, a palladium layer proximate the gold layer, and a diffusion barrier layer proximate the palladium layer, the diffusion barrier layer including nickel and having a thickness that is less than about the skin depth of nickel at 0.9 GHz. Other embodiments of the module are provided along with related methods and components thereof.

Abstract: 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.

Abstract: Apparatus and methods for biasing a power amplifier are provided. In one embodiment, a packaged circuit includes a power amplifier, a bond wire electrically connected between a system voltage source and a supply input of the power amplifier, a current source, a reference resistor electrically connected between the system voltage source and the current source, and a comparator. The comparator is configured to compare a sense voltage that is based on a voltage across the bond wire to a reference voltage that is based on a voltage across the reference resistor. The comparator is configured to generate a saturation control signal for clamping a bias current of the power amplifier when the sense voltage exceeds the reference voltage.

Abstract: A voltage converter can be switched among two or more modes to produce an output voltage tracking a reference voltage that can be of an intermediate level between discrete levels corresponding to the modes. One or more voltages generated from a power supply voltage, such as a battery voltage, can be compared with the reference voltage to determine whether to adjust the mode. The reference voltage can be independent of the power supply voltage.

Abstract: Apparatus and methods for envelope tracking are disclosed. In one embodiment, a power amplifier system including a power amplifier and an envelope tracker is provided. The power amplifier is configured to amplify a radio frequency (RF) signal, and the envelope tracker is configured to control a supply voltage of the power amplifier using an envelope of the RF signal. The envelope tracker includes a buck converter for generating a buck voltage from a battery voltage and a digital-to-analog conversion (DAC) module for adjusting the buck voltage based on the envelope of the RF signal to generate the supply voltage for the power amplifier.

Abstract: Apparatus and methods for envelope tracking calibration are provided. In one embodiment, a method of calibrating an envelope tracker having an envelope shaping table generated at a desired gain compression of a power amplifier is provided. The method includes generating a supply voltage for the power amplifier using the envelope tracker, operating the supply voltage of the power amplifier at a first voltage level associated with substantially no gain compression of the power amplifier, and measuring an output power of the power amplifier at the first voltage level. The method further includes decreasing a voltage level of the supply voltage one or more times and measuring the output power at each voltage level, determining a second voltage level of the power amplifier associated with a gain compression equal to about that of the desired gain compression, and calibrating the envelope tracker based on the determination.

Abstract: Apparatus and methods for biasing a power amplifier are provided. In one embodiment, a packaged circuit includes a power amplifier, a bond wire electrically connected between a system voltage source and a supply input of the power amplifier, a current source, a reference resistor electrically connected between the system voltage source and the current source, and a comparator. The comparator is configured to compare a sense voltage that is based on a voltage across the bond wire to a reference voltage that is based on a voltage across the reference resistor. The comparator is configured to generate a saturation control signal for clamping a bias current of the power amplifier when the sense voltage exceeds the reference voltage.

Abstract: An integrated image reject mixer (150) generates precise quadrature components using highly matched local-oscillator (LO) path and intermediate frequency (IF) path resistor-capacitor (RC) phase shifting networks (131, 138). Because the LO signal from a local oscillator (127) has a constant amplitude, a phase detector (136) feedback loop easily maintains an accurate ninety-degree phase difference between the quadrature LO signals (122, 124) from the LO path phase shifting network (131). Because the two phase shifting networks are matched, the feedback control signal (137) from the phase detector (136) can also be used to maintain an accurate ninety-degree phase difference between the quadrature IF signals (123, 128) from the IF path phase shifting network (138) despite the dynamically-varying amplitude of the IF signal. Thus, this image reject mixer uses only components that may be easily integrated into an integrated circuit.