A difference between subsequent measures of a second signal when a first signal crosses a threshold value can be used to estimate a delay between the first and second signal. The delay can be used to compensate for delays between an envelope power supply signal and a radio frequency (RF) input signal.

A system for adjusting various parameters of an active electronic component based on sensed characteristics of the active electronic component and/or characteristics of the input or output power.

Target voltage generation in an envelope tracking (ET) integrated circuit (ETIC) is provided. The ETIC is configured to generate a time-variant ET voltage based on a time-variant target voltage for amplifying a radio frequency (RF) signal modulated for communication in multiple time intervals. In embodiments disclosed herein, the ETIC is self-contained to generate the time-variant target voltage based on a sensed signal having a time-variant sensed envelope that tracks a time-variant power envelope of the RF signal. Since the time-variant target voltage is generated to track the time-variant sensed envelope, which further tracks the time-variant power envelope, the time-variant ET voltage can better track the time-variant power envelope of the RF signal when the time-variant ET voltage is provided to a power amplifier(s) that amplifies the RF signal.

A power management circuit operable with group delay is provided. The power management circuit includes a transceiver circuit configured to generate a digital target voltage and digitally delay the digital target voltage to generate multiple delayed digital target voltages. Accordingly, the transceiver circuit can generate a windowed digital target voltage in multiple delay tolerance windows based on the delayed digital target voltages. Since the windowed digital target voltage can tolerate a certain amount of group delay in each of the group delay tolerance windows, an envelope tracking (ET) voltage generated based on an analog version of the windowed digital target voltage can therefore tolerate the group delay in each of the group delay tolerance windows as well. As a result, it is possible to avoid distortion in the ET voltage to help improve performance of the power management circuit.

A power amplifier system front end measures both forward and reverse power associated with an RF transmit signal. A processor is configured to use measurements derived from the measured forward and reverse power output to adjust the RF transmit signal in order to compensate for one or more memory effects of the power amplifier system.

Circuits, systems, devices, and methods related to transistors with Schottky barriers are discussed herein. For example, a method of fabricating a transistor can include forming a p-well or an n-well in a substrate and forming a gate for the transistor. The method can also include doping a region within the p-well or n-well with a concentration below a threshold and forming a conductor layer on the doped region.

Apparatus and methods for power amplifiers with positive envelope feedback are provided herein. In certain implementations, a power amplifier system includes a power amplification stage that amplifies a radio frequency signal, at least one envelope detector that generates one or more detection signals indicating an output signal envelope of the power amplification stage, and a wideband feedback circuit that provides positive envelope feedback to a bias of the power amplification stage based on the one or more detection signals. The power amplifier system further includes a supply modulator that controls a voltage level of a supply voltage of the power amplification stage based on the one or more detection signals such that the supply voltage is modulated with the output signal envelope through positive envelope feedback.

A radio-frequency circuit is capable of simultaneously transmitting a radio-frequency signal of a middle high band group (MHB) including B1 and B3, and a radio-frequency signal of a ultra-high band group (UHB) including n77, and includes: a first transfer circuit that transfers the MHB radio-frequency signal and a radio-frequency signal of a low band group (LB); and a second transfer circuit that transfers the UHB radio-frequency signal. The first transfer circuit includes: a power amplifier for B1 signals; a diplexer that demultiplexes and/or multiplexes the MHB radio-frequency signal and the LB radio-frequency signal; a transmission filter that is connected to the power amplifier and has, as a passband, a transmission band of B1; and a band-elimination filter that is disposed between the diplexer and the transmission filter, and has, as an attenuation band, a transmission band of n77. The second transfer circuit includes a power amplifier for n77 signals.

A power amplifier module includes an output-stage amplifier, a driver-stage amplifier, an input switch, an output switch, an input matching circuit, an inter-stage matching circuit, an output matching circuit, and a control circuit. The input switch selectively connects one of a plurality of input signal paths to an input terminal of the driver-stage amplifier. The output switch selectively connects one of a plurality of output signal paths to an output terminal of the output-stage amplifier. The control circuit controls operations of the driver-stage amplifier and the output-stage amplifier. The input switch, the output switch, and the control circuit are integrated into an IC chip. The control circuit is disposed between the input switch and the output switch.

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.