A method and an apparatus for envelope shaping of a multi-carrier signal in envelope tracking transmission are disclosed. According to an embodiment, a baseband version of an envelope portion belonging to each of multiple carriers in the multi-carrier signal is positioned such that a frequency spacing between adjacent positioned envelope portions is smaller than that between corresponding adjacent carriers. The positioned envelope portions are combined into a composite envelope. The composite envelope is shaped. The shaped composite envelope is split into baseband versions of shaped envelope portions belonging to the multiple carriers. The baseband version of each shaped envelope portion is repositioned such that a frequency spacing between adjacent repositioned envelope portions is equal to that between corresponding adjacent carriers.

A supply modulator is provided, having a first amplifier circuit configured to generate a first electrical signal, a second amplifier circuit configured to generate a second electrical signal, the first and second electrical signals being for driving an electrical load, and a control circuit electrically coupled to the first and second amplifier circuits wherein the control circuit is configured to generate a pulsed electrical signal and to supply an output control signal to the second amplifier circuit for controlling generation of the second electrical output signal, wherein the supply modulator is configured to operate in two modes of operation, for the first amplifier circuit to generate the first electrical signals in response to quiescent current of the first amplifier circuit, for the control circuit to generate a modulated electrical signal in accordance with a clock signal in one mode, and, for the second amplifier circuit to operate at different frequencies.

Methods and systems for power amplification of time varying envelope signals are disclosed herein. In one embodiment, a plurality of signals with constant envelope generated from the decomposition of the quantized version of a time varying envelope signal are individually amplified and then summed to form a desired time-varying envelope signal. Amplitude, phase and frequency characteristics of one or more of the constituent signals are controlled to provide the desired phase, frequency, and/or amplitude characteristics of the desired time varying envelope signal. In another embodiment, a time-varying envelope signal is decomposed into in-phase and quadrature components that are quantized and decomposed into a plurality of quasi constant or constant envelope constituent signals. The constituent signals are amplified, and then summed to construct an amplified version of the original time-varying envelope signal. The signal amplifiers may be Class A, B, AB, C, D, Class F or Class S amplifiers to provide high amplification efficiency.

A method and an apparatus for envelope shaping of a multi-carrier signal in envelope tracking transmission are disclosed. According to an embodiment, a baseband version of an envelope portion belonging to each of multiple carriers in the multi-carrier signal is positioned such that a frequency spacing between adjacent positioned envelope portions is smaller than that between corresponding adjacent carriers. The positioned envelope portions are combined into a composite envelope. The composite envelope is shaped. The shaped composite envelope is split into baseband versions of shaped envelope portions belonging to the multiple carriers. The baseband versions of each shaped envelope portion is repositioned such that a frequency spacing between adjacent repositioned envelope portions is equal to that between corresponding adjacent carriers.

A power supply configured to supply a modulated voltage to a power amplifier is shown. The power supply has an alternating current (AC) component generator, a direct current (DC) component generator, and a transition accelerator. The AC component generator generates an AC component of the modulated voltage according to an envelope tracking signal. The DC component generator generates a DC component of the modulated voltage according to the operational voltage range of the power amplifier. The transition accelerator is coupled to an output terminal of the DC component generator to speed up the transition of the modulated voltage.

A multi-amplifier envelope tracking (ET) circuit and related apparatus are provided. The multi-amplifier ET circuit includes a number of amplifier circuits configured to amplify concurrently a radio frequency (RF) signal to generate a number of amplified RF signals for concurrent transmission, for example, in a millimeter wave (mmWave) spectrum. The amplifier circuits are configured to amplify the RF signal based on a number of ET voltages and a number of low-frequency currents, respectively. A number of driver circuits is provided in the multi-amplifier ET circuit to generate the ET voltages and the low-frequency currents for the amplifier circuits, respectively. In examples discussed herein, the driver circuits are co-located with the amplifier circuits to help improve efficiency and maintain linearity in the amplifier circuits, particularly when the RF signal is modulated at a higher modulation bandwidth (e.g., >80 MHz).

An envelope tracking (ET) integrated circuit (IC) (ETIC) is provided. The ETIC includes a number of ET circuits coupled to a number of amplifier circuits configured to amplify a radio frequency signal based on a number of ET voltages, respectively. The ET circuits are configured to generate the ET voltages based on a number of ET target voltages, respectively. The ETIC includes a reference ET circuit configured to generate a reference ET voltage based on a maximum ET target voltage among the ET target voltages. A selected ET circuit(s) among the ET circuits may be configured to not generate a respective ET voltage(s) but instead forward the reference ET voltage to a respective amplifier circuit(s) as the respective ET voltage(s). Hence, it may be possible to partially or completely turn off the selected ET circuit(s) to help reduce peak battery current and improve heat dissipation in an ET amplifier apparatus.

An envelope tracking (ET) power amplifier apparatus is provided. In a non-limiting example, the ET power amplifier apparatus includes a single ET integrated circuit (ETIC) configured to support at least a pair of amplifier circuits for amplifying different radio frequency (RF) signals. One of the amplifier circuits may be configured to amplify a respective RF signal to a higher power and thus will operate based on an ET voltage whenever possible. Another amplifier circuit, on the other hand, may be configured to amplify a respective RF signal to a relatively lower power and thus will only operate based on the ET voltage when the other amplifier circuit is inactive. By employing a single ETIC, it may be possible to reduce footprint of the ET power amplifier apparatus, thus making it possible to fit the ET power amplifier apparatus into a small form factor electronic device, such as a wearable device.

Apparatus and methods for biasing power amplifiers are provided herein. In certain embodiments, a power amplifier includes a bipolar transistor having a base biased by a bias network having a reactance that controls an impedance at the transistor base to achieve substantially flat phase response over large dynamic power levels. For example, the bias network can have a frequency response, such as a high-pass or band-pass response, that reduces the impact of power level on phase distortion (AM/PM).

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.