Qorvo US, Inc.

Rf Micro Devices, Inc.

James M Retz

Nadim Khlat

Andrew F Folkmann

Ruediger Bauder

Michael R Kay

Jean-Frederic Chiron

Chris Levesque

Christopher Truong Ngo

Arthur Nguyen

Jeff Kaminski

Envelope tracking power supply circuitry includes a look up table (LUT) configured to provide a target supply voltage based on a power envelope measurement. The target supply voltage is dynamically adjusted based on a delay between the power envelope of an RF signal and a provided envelope tracking supply voltage. The envelope tracking supply voltage is generated from the adjusted target supply voltage in order to synchronize the envelope tracking supply voltage with the power envelope of the RF signal.

Systems and methods for providing an envelope tracking supply voltage

Circuit and method for inter-symbol and intra-symbol voltage method are disclosed. Herein, a transceiver circuit is configured to determine a voltage target(s) for generating a modulated voltage(s) to amplify a radio frequency (RF) signal modulated in multiple symbols. Specifically, the transceiver circuit will generate multiple voltage targets for any of the symbols to thereby enable intra-symbol voltage modulation when the respective symbol is modulated to carry a selected type of information or generate a single voltage target for any of the symbols to thereby enable inter-symbol voltage modulation when the respective symbol lacks the selected type of information. By dynamically performing inter-symbol and intra-symbol voltage modulation based on the type of information carried in a symbol(s), the modulated voltage can be timely adapted to closely track a time-variant power envelope of the RF signal to thereby avoid potential distortion and protect critical information in the RF signal.

Circuit and method for inter-symbol and intra-symbol voltage modulation

Envelope tracking (ET) voltage correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant modulation vector and the power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit. Herein, the transceiver circuit is configured to apply an equalization filter to a selected form of the time-variant modulation vector to compensate for a voltage distortion filter created across a modulation bandwidth of the RF signal(s) by coupling the power amplifier circuit with the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s) across the modulation bandwidth of the RF signal(s).

Envelope tracking voltage correction in a transmission circuit

Equalizer circuitry includes a differential target voltage input, an equalizer output, a first operational amplifier, and a second operational amplifier. The differential target voltage input includes a target voltage input node and an inverted target voltage input node. The first operational amplifier and the second operational amplifier are coupled in series between the differential target voltage input and the equalizer output. The first operational amplifier is configured to receive a target voltage signal and provide an intermediate signal based on the target voltage input signal. The second operational amplifier is configured to receive the intermediate signal and an inverted target voltage signal and provide an output signal to the equalizer output. The first operational amplifier and the second operational amplifier are interconnected with one or more passive components such that a transfer function between the differential target voltage input and the equalizer output is a second-order complex-zero function.

Equalizer for envelope power supply circuitry

A wideband transmission circuit is provided. The wideband transmission circuit includes a transceiver circuit and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant input vector and provides the RF signal(s) to the power amplifier circuit(s). The power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit (e.g., filter/multiplexer circuit). In embodiments disclosed herein, the transceiver circuit is configured to apply an equalization filter to the time-variant input vector to thereby compensate for a voltage distortion filter caused by a coupling of the power amplifier circuit(s) and the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s).

Wideband transmission circuit

Equalization filter calibration in a wideband transmission circuit is provided. The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant modulation vector and a power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage. The transceiver circuit is configured to apply an equalization filter to the time-variant modulation vector to thereby compensate for a voltage distortion filter created at the output stage of the power amplifier circuit(s). In embodiments disclosed herein, a calibration circuit can be configured to calibrate the equalization filter across multiple frequencies within a modulation bandwidth of the power amplifier circuit to generate a gain offset lookup table (LUT) and a delay LUT. As a result, the equalization filter can be dynamically adapted to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter across the modulation bandwidth of the power amplifier circuit.

Equalization filter calibration in a transceiver circuit

Envelope tracking (ET) voltage correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant modulation vector and the power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit. Herein, the transceiver circuit is configured to apply a complex filter(s) to the time-variant modulation vector and/or the RF signal(s) to compensate for a voltage distortion filter created across a modulation bandwidth of the RF signal(s) by coupling the power amplifier circuit with the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s) across the modulation bandwidth of the RF signal(s).

An envelope tracking (ET) amplifier circuit is provided. The ET amplifier circuit includes an amplifier circuit configured to amplify a radio frequency (RF) signal based on an ET modulated voltage. The ET modulated voltage corresponds to a time-variant voltage envelope, which can be misaligned from a time-variant signal envelope of the RF signal due to inherent temporal delay in the ET amplifier circuit. As a result, the amplifier circuit may suffer degraded linearity performance. In this regard, a voltage processing circuit is provided in the ET amplifier circuit and configured to operate in a low-bandwidth mode and a high-bandwidth mode. In the high-bandwidth mode, the voltage processing circuit is configured to cause the ET modulated voltage to be modified to help improve delay tolerance of the ET amplifier circuit. As a result, it may be possible to reduce linearity degradation of the amplifier circuit to a predetermined threshold.

Envelope tracking amplifier circuit

An envelope tracking (ET) amplifier circuit is provided. The ET amplifier circuit includes an ET voltage circuit configured to generate an ET modulated voltage based on a supply voltage for amplifying a radio frequency (RF) signal. The ET modulated voltage corresponds to a time-variant voltage envelope, which can be misaligned from a time-variant signal envelope of the RF signal due to an inherent temporal delay in the ET amplifier circuit. A voltage processing circuit is provided in the ET amplifier circuit to reduce dynamic range of the ET modulated voltage to help improve delay sensitivity in the ET amplifier circuit. A control circuit is configured to reduce the supply voltage according to the dynamic range to help maintain system-wide efficiency of the ET amplifier circuit at a defined level. As such, it may be possible to improve delay sensitivity and maintain sufficient system-wide efficiency in the ET amplifier circuit.

Nonlinear bandwidth compression circuitry is provided. In examples discussed herein, nonlinear bandwidth compression circuitry can be configured to modify predefined amplitude(s) of a predefined voltage waveform to generate modified amplitude(s) of a modified voltage waveform that is never less than the predefined amplitude(s) of the predefined voltage waveform. Thus, by providing the nonlinear bandwidth compression circuitry in an envelope tracking (ET) system to perform bandwidth compression, signal distortion(s) resulted from the bandwidth compression can be corrected (e.g., via digital pre-distortion). As such, the ET system can amplify a radio frequency (RF) signal having a signal modulation bandwidth exceeding a voltage modulation bandwidth limitation of the ET system, without degrading spectral performance of the RF signal.

Nonlinear bandwidth compression circuitry

Disclosed is an envelope tracking (ET) system having a transmit (TX) section, a power amplifier (PA), a fast switched-mode power supply (Fast SMPS), and control circuitry. The TX section receives an input signal and provides a modulated signal to the PA. The TX section also generates an ET signal based on a modulation envelope of the modulated signal. The TX section provides an envelope control (EC) signal based on the ET signal to modulate a supply signal provided to the PA by the Fast SMPS. The control circuitry provides a transmit TX gain signal and an ET gain signal to the TX section based on a PA temperature signal, a TX temperature signal, a target power signal, a measured power signal. The control circuitry is configured to maintain the efficiency and linearity of the PA over a wide operating temperature range.

Temperature compensation technique for envelope tracking system

A method of defining a quasi iso-gain supply voltage function for an envelope tracking system is disclosed. The method includes a step of capturing iso-gain supply voltage values versus power values for a device under test (DUT). Other steps involve locating a minimum iso-gain supply voltage value, and then replacing the iso-gain supply voltage values with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value. The method further includes a step of generating a look-up table (LUT) of iso-gain supply voltage values as a function of input power for the DUT after the step of replacing the iso-gain supply voltage values with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value.

Quasi iso-gain supply voltage function for envelope tracking systems

A circuit and method is disclosed that dithers a switching frequency of a DC-to-DC converter which gets modulated onto an RF carrier such that switching noise is spread over a given bandwidth that is wider than a communications measurements bandwidth. The circuit includes a switching circuitry adapted to transfer energy from a source to a load using a switching signal having a series of switching cycles and a switching frequency. Also included is a control circuitry adapted to generate a pseudo-random value near a beginning of each of the series of switching cycles to determine a maximum switching frequency value based upon the pseudo-random value. The method includes adjusting the switching frequency of the switching signal incrementally from a fixed minimum switching frequency value to the maximum frequency value and vice versa as a function of time during each of the series of switching cycles of the switching circuit.

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Cedar Rapids, IA, United States of America

James M Retz