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Patent

Multi-mode amplifier system

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TLDR
In this article, an amplifier system switches between modes of operation based upon a characteristic of an input signal relative to a first threshold level and a second threshold level, and a mode selector selects the operation mode by transmitting an amplitude modulated signal plus a variable headroom voltage to a supply terminal of a power amplifier during the envelope tracking mode, an amplitude and phase modulated input signal during the polar mode and a substantially constant amplitude signal to the supply terminal during the linear mode.
Abstract
An amplifier system is provided that switches between a linear mode of operation, an envelope tracking mode of operation and a polar mode of operation. The amplifier system switches between modes of operation based upon a characteristic of an input signal relative to a first threshold level and a second threshold level. A mode selector selects the operation mode by transmitting an amplitude modulated signal plus a variable headroom voltage to a supply terminal of a power amplifier during the envelope tracking mode, an amplitude modulated signal to the supply terminal and phase modulated input signal during the polar mode and a substantially constant amplitude signal to the supply terminal during the linear mode.

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Citations
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Patent

Multi-mode/multi-band power management system

TL;DR: In this article, a power management system for a radio frequency (RF) power amplifier (PA) load is described, which includes a first switching power supply that is adapted to output a relatively constant voltage, an electronic switch for selectively coupling the first switch power supply to the RF PA load, and a second switching power that outputs a dynamic DC voltage to the PA load.
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TL;DR: In this article, a transceiver for an envelope following system is described, which includes a power amplifier having a signal input, a signal output, and a power input that receives power from a power management system that modulates a supply voltage provided to the PA in response to an envelope signal.
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Noise reduction for envelope tracking

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Multiple power supply input parallel amplifier based envelope tracking

TL;DR: In this paper, a switch mode power supply converter and a parallel amplifier are described, where the switch mode converter is coupled to a modulated power supply output and the parallel amplifier has a parallel output coupled to the modulated output.
References
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Journal ArticleDOI

High-efficiency power amplifier using dynamic power-supply voltage for CDMA applications

TL;DR: In this article, a boost DC-DC converter with an operating frequency of 10 MHz is demonstrated using GaAs heterojunction bipolar transistors, and an envelope detector circuit with a fast feedback loop regulator is discussed.
Patent

Method and apparatus for operating a radio-frequency power amplifier as a variable-class linear amplifier

TL;DR: In this paper, a variable-class linear amplifier (600, 800, 900) applies a supply type of envelope modulation to an RF power amplifier operating in or near compression at highest envelope amplitudes, and transitions gradually to an envelope tracking type of operation at intermediate amplifier amplitudes.
Patent

Method and apparatus for generating a linearly modulated signal using polar modulation

TL;DR: In this article, an apparatus and method for generating a linearly modulated signal in a polar modulation system is described, where a signal for transmission is separated into a phase component and an amplitude component, and a carrier signal is modulated with the phase component in a phase modulator, creating a phase distortion.
Patent

RF transmitter with extended efficient power control range

TL;DR: A highly efficient radio frequency (RF) transmitter provides both wide bandwidth and an extended power control range as mentioned in this paper, which is useful in wireless communications to increase both handset talk time and battery life.
Patent

Method, device, phone and base station for providing envelope-following for variable envelope radio frequency signals

TL;DR: In this paper, an envelope-following unit is used to output a supply voltage in accordance with a variable envelope of an input baseband signal, wherein using the efficient envelope following unit includes: 1) using a bandwidth-limiting mapping unit to determine a reference signal based on the base band signal; and 2) using an envelope tracking power converter to output the supply voltage, responsive to the reference signal, to the linear RF power amplifier.