Patent•
Multi-mode amplifier system
24 Jun 2003-
TL;DR: 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.
Citations
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11 Jul 2006TL;DR: In this paper, a media broadcast and distribution system is described which substitutes storage for communications, allowing more efficient use of scarce bandwidth resources, allowing a terrestrial FM broadcaster to offer a larger number of higher quality audio channels than satellite radio services such as Sirius and XM Satellite Radio.
Abstract: A media broadcast and distribution system is disclosed which substitutes storage for communications, allowing more efficient use of scarce bandwidth resources. One embodiment allows a terrestrial FM broadcaster to offer a larger number of higher quality audio channels than current satellite radio services such as Sirius and XM Satellite Radio. This embodiment also has features that offer a better user experience than with personal audio devices such as Apple's iPod™. Another embodiment allows satellite radio services to expand their video offerings.
166 citations
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03 Sep 2008TL;DR: In this article, a multi-mode transmitter that is configurable to operate in a plurality of operating modes (e.g., a polar mode, a quadrature mode and a hybrid mode), a receiver, and an operating mode controller is presented.
Abstract: Methods and apparatus for transmitting communications signals that are both power efficient and effective at avoiding or reducing transmitter-generated receive band noise. An exemplary transceiver apparatus includes a multi-mode transmitter that is configurable to operate in a plurality of operating modes (e.g., a polar mode, a quadrature mode and a hybrid mode), a receiver, and an operating mode controller. The operating mode controller is configured to control which operating mode the transmitter is to operate, depending on one or more of a transmit (Tx) power, receive (Rx) power, the Tx power relative to the Rx power, a level of frequency separation between a Tx frequency band and a Rx frequency band (Tx/Rx band separation), and modulation type employed by the transmitter.
157 citations
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24 Oct 2008TL;DR: A transceiver comprises an amplifying circuit for amplifying an input signal to produce an output signal, and a power supply is operable for varying the level of power supplied to the Amplifying circuit in response to a variation of the input signal envelope directed to the power supply as discussed by the authors.
Abstract: A transceiver comprises an amplifying circuit for amplifying an input signal to produce an output signal A power supply is operable for varying the level of power supplied to the amplifying circuit in response to variation of an input signal envelope directed to the power supply A processing circuit is operable for digitally detecting the input signal envelope to provide variation of the power supply level The processing circuit is further operable for digitally delaying the digital input signal envelope to time align the power supply level with the input signal
143 citations
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27 Aug 2013TL;DR: In this paper, an envelope power supply calibration of a multi-mode RF power amplifier (PA) was proposed to ensure adequate headroom when operating using one of multiple communications modes. But, the power supply was not restricted to provide a minimum allowable magnitude based on an RF signal level of the PA.
Abstract: The present disclosure relates to envelope power supply calibration of a multi-mode RF power amplifier (PA) to ensure adequate headroom when operating using one of multiple communications modes. The communications modes may include multiple modulation modes, a half-duplex mode, a full-duplex mode, or any combination thereof. As such, each communications mode may have specific peak-to-average power and linearity requirements for the multi-mode RF PA. As a result, each communications mode may have corresponding envelope power supply headroom requirements. The calibration may include determining a saturation operating constraint based on calibration data obtained during saturated operation of the multi-mode RF PA. During operation of the multi-mode RF PA, the envelope power supply may be restricted to provide a minimum allowable magnitude based on an RF signal level of the multi-mode RF PA, the communications mode, and the saturation operating constraint to provide adequate headroom.
111 citations
References
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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.
Abstract: Efficiency and linearity of the microwave power amplifier are critical elements for mobile communication systems. This paper discusses improvements in system efficiency that are obtainable when a DC-DC converter is used to convert available battery voltage to an optimal supply voltage for the output RF amplifier. A boost DC-DC converter with an operating frequency of 10 MHz is demonstrated using GaAs heterojunction bipolar transistors. Advantages of 10 MHz switching frequency and associated loss mechanisms are described. For modulation formats with a time-varying envelope, such as CDMA, the probability of power usage is described. Gains in power efficiency and battery lifetime are calculated. An envelope detector circuit with a fast feedback loop regulator is discussed. Effects of varying supply voltage with respect to distortion are examined along with methods to increase system linearity.
395 citations
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07 Jan 1999TL;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.
Abstract: 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 envelope amplitudes. The amplifier further transitions gradually to a linear class of operation with a constant supply voltage (508) at lowest envelope amplitudes.
296 citations
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06 Oct 1999TL;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.
Abstract: An apparatus and method generate a linearly modulated signal in a polar modulation system. 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. A compensator compensates for the phase distortion created by the phase modulator by modifying the amplitude component. The phase modulated carrier signal is amplitude modulated by the compensated amplitude component to produce a linearly modulated signal.
178 citations
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11 Jan 2000TL;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.
Abstract: A highly efficient radio frequency (RF) transmitter provides both wide bandwidth and an extended power control range. The RF transmitter includes stage switching, bias adjustment, and drain supply modulation. These components are used to provide fine and coarse power control and EER envelope fluctuations. The RF transmitter is useful in wireless communications to increase both handset talk time and battery life.
170 citations
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31 Dec 1997TL;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.
Abstract: A method (200) and device (100) provide an efficient linear power amplifier that generates a variable-envelope radio frequency RF signal. The method includes the steps of: A) using an efficient envelope-following unit 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 baseband signal; and 2) using an envelope-tracking power converter to output a supply voltage, responsive to the reference signal, to the linear RF power amplifier; B) providing an RF input signal with amplitude and phase information to a linear RF power amplifier; and C) using the linear RF power amplifier to output a power-efficient amplified variable-envelope RF signal with substantially a same amplitude and phase information as the RF input signal.
152 citations