A digital isolator comprising a set of bipolar transistors and an inductor capacitor (LC) oscillator coupled to the set of bipolar transistors in series, wherein the LC oscillator is configured to be turned on and off based on the current applied to the set of bipolar transistors or the LC oscillator and generate a set of differential signals based on the current flowing through the set of bipolar transistors and mimicking the operational characteristics of an optocoupler.

An envelope tracking (ET) integrated circuit (ETIC) operable across wide modulation bandwidth is disclosed. The ETIC includes at least two auxiliary voltage outputs coupled to a high-bandwidth power amplifier circuit that has a lower equivalent capacitance, and thus a higher impedance resonance frequency. The ETIC also includes a pair of ET voltage circuits configured to generate a pair of ET voltages, respectively. To help mitigate potential distortion in the ET voltages, a control circuit is configured to couple the ET voltage circuits exclusively to the auxiliary voltage outputs when the ETIC needs to operate with a high modulation bandwidth (e.g., 200 MHz). Given the higher impedance resonance frequency of the high-bandwidth power amplifier circuit, it is possible to increase separation between an energy spectrum of a voltage disturbance and an energy spectrum of the high modulation bandwidth, thus helping to reduce the potential distortion in the ET voltages.

A device for digital envelope tracking with dynamically changing voltage levels for a radio frequency (RF) power amplifier is disclosed. A power management unit generates a set of supply voltages for a power amplifier based on a control signal. A setpoint generator in the power management integrated circuit gradually increases or decreases a target voltage such that the set of supply voltages output from the voltage converter gradually increase or decrease in response to a gradual transition of the target voltage. A transceiver includes digital models for replicating a behavior of the setpoint generator and a voltage regulator in the voltage converter such that a signal pre-distortion unit may use an instantaneous voltage level for signal predistortion.

A power amplifier circuit includes an amplifier transistor having a first terminal supplied with a power supply voltage that changes in accordance with an amplitude level of an input signal, and a second terminal supplied with the input signal and a bias current, an amplified signal obtained by amplifying the input signal being outputted from the first terminal, a bias circuit that outputs the bias current from an output terminal thereof in accordance with a reference current supplied to an input terminal thereof, and a regulation circuit that generates a regulation current for regulating the bias current in accordance with a change in the power supply voltage. The regulation current increases with an increase in the power supply voltage, and decreases with a decrease in the power supply voltage. The regulation circuit extracts the regulation current from at least one of the reference current or the bias current.

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 dual-output and dual-mode supply modulator, a two-stage power amplifier using the same, and a supply modulation method therefor are provided. In order to improve the performance of a two-stage power amplifier used in a transmitter of a wireless communication system, the dual-output and dual-mode supply modulator according to the present invention may simultaneously supply an envelope tracking signal to a main amplification stage of the two-stage power amplifier and an average power tracking signal to an auxiliary amplification stage thereof. To this end, the dual-output and dual-mode supply modulator according to the present invention outputs two supply voltages and supports two operation modes. As such, it is possible to improve the efficiency of the two-stage power amplifier over a wide output power range with the use of a single supply modulator by employing envelope tracking on the main amplification stage and average power tracking on the auxiliary amplification stage in high output power regions or employing average power tracking both on the main amplification stage and auxiliary amplification stage in low output power regions.

Systems, circuitries, and methods for predistorting a digital signal in a transmit chain based on a predistortion function are provided in which the function is determined based on a first digital signal or a first transmit chain state. A method includes: receiving a second digital signal that is input to the transmit chain, wherein the transmit chain is characterized by a present transmit chain state; performing a first operation on the second digital signal to generate an adapted digital signal, wherein the first operation is based on either a relationship between the first digital signal and the second digital signal, or a relationship between the first transmit chain state and the present transmit chain state; predistorting the adapted digital signal based on the predistortion function; and performing a second operation on the predistorted adapted signal, wherein the second operation corresponds to an inverse of the first operation.

An envelope tracking (ET) circuit is provided. In examples discussed herein, the ET circuit can be configured to operate in a fifth-generation (5G) standalone (SA) mode and a 5G non-standalone (NSA) mode. In the SA mode, the ET circuit can enable a first pair of ET power amplifier circuits to amplify a 5G signal based on ET for concurrent transmission in a 5G band(s). In the NSA mode, the ET circuit can enable a second pair of ET power amplifier circuits to amplify an anchor signal and a 5G signal based on ET for concurrent transmission in an anchor band(s) and a 5G band(s), respectively. As such, the ET circuit may be provided in a 5G-enabled wireless communication device (e.g., a 5G-enabled smartphone) to help improve power amplifier linearity and efficiency in both 5G SA and NSA networks.

An envelope tracking (ET) amplifier apparatus is provided. In examples discussed herein, the ET amplifier apparatus can be configured to operate in a fifth-generation (5G) standalone (SA) mode and a 5G non-standalone (NSA) mode. In the SA mode, the ET amplifier apparatus can enable a first pair of amplifier circuits to amplifier a 5G signal for concurrent transmission in a 5G band(s). In the NSA mode, the ET amplifier apparatus can enable a second pair of amplifier circuits to amplify a non-5G anchor signal and a 5G signal for concurrent transmission in a non-5G anchor band(s) and a 5G band(s), respectively. As such, the ET circuit may be provided in a communication apparatus (e.g., a 5G-enabled smartphone) to help improve power amplifier linearity and efficiency in both 5G SA and NSA modes.

A multi-mode envelope tracking (ET) target voltage circuit is provided. In an ET amplifier apparatus, an amplifier circuit is configured to amplify a radio frequency (RF) signal based on a time-variant ET voltage, which is generated based on a time-variant ET target voltage configured to track a time-variant power envelope of the RF signal. Notably, when the ET amplifier apparatus operates in a fifth-generation (5G) standalone (SA) or non-standalone (NSA) mode, the amplifier circuit may experience interference creating a reverse intermodulation product (rIMD) that can degrade efficiency and performance of the amplifier circuit. In examples discussed herein, the multi-mode ET target voltage circuit is configured to generate the ET target voltage based on a reduced slew rate to help suppress the rIMD at the amplifier circuit, thus making it possible to improve efficiency and performance of the ET amplifier apparatus in the SA and the NSA modes.