Rf Micro Devices, Inc.

Brian Baxter

Roman Zbigniew Arkiszewski

Chris Levesque

David E Jones

Terry J Stockert

William David Southcombe

Scott Yoder

Jason Millard

Steven Selby

Hirofumi Honjo

Stuart Williams

David Durgin Coons

Nadim Khlat

Wael Al-Qaq

Dennis Mahoney

Paul Brey

Brad Hunkele

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.

Envelope power supply calibration of a multi-mode radio frequency power amplifier

A charge pump of a power amplifier (PA) bias power supply and a process to prevent undershoot disruption of a bias power supply signal of the PA bias power supply are disclosed. The charge pump operates in one of multiple bias supply pump operating modes, which include at least a bias supply pump-up operating mode and a bias supply bypass operating mode. The process prevents selection of the bias supply pump-up operating mode from the bias supply bypass operating mode before charge pump circuitry in the charge pump is capable of providing adequate voltage to prevent undershoot disruption of the bias power supply signal.

PA bias power supply undershoot compensation

Power amplifier (PA) control circuitry and PA bias circuitry are disclosed. During one slot of a multislot transmit burst from radio frequency (RF) PA circuitry, the PA control circuitry selects one PA bias level of the RF PA circuitry and the RF PA circuitry has one output power level. The RF PA circuitry has a next output power level during an adjacent next slot of the multislot transmit burst. If the one output power level exceeds the next output power level by more than a power drop limit, then the PA control circuitry maintains the one PA bias level during the adjacent next slot. If the one output power level significantly exceeds the next output power level, but by less than the power drop limit, then the PA control circuitry selects a next PA bias level, which is less than the one PA bias level, during the adjacent next slot.

Selecting PA bias levels of RF PA circuitry during a multislot burst

A radio frequency (RF) communications system, which includes power amplifier (PA) control circuitry and PA bias circuitry, is disclosed. The PA control circuitry identifies a selected communications mode of the RF communications system and a target output power from RF PA circuitry. The PA control circuitry selects a PA bias level of a driver stage of the RF PA circuitry and a PA bias level of a final stage of the RF PA circuitry based on the selected communications mode and the target output power. The PA bias circuitry establishes a PA bias level for the driver stage and a PA bias level for the final stage based on the selected PA bias levels of the driver stage and the final stage, respectively.

Independent PA biasing of a driver stage and a final stage

A direct current (DC)-DC converter and radio frequency (RF) power amplifier (PA) circuitry are disclosed. The DC-DC converter provides an envelope power supply signal to the RF PA circuitry based on a first power supply output control signal. As a temperature of the RF PA circuitry changes, the envelope power supply signal may need to be adjusted to meet temperature compensation requirements of the RF PA circuitry. With adequate thermal coupling between the DC-DC converter and the RF PA circuitry, adjustments to the envelope power supply signal may be based on temperature measurements of the DC-DC converter. A desired correction of the first power supply output control signal is determined based on a measured temperature of the DC-DC converter and the temperature compensation requirements of the RF PA circuitry. The first power supply output control signal is adjusted based on the desired correction.

Temperature correcting an envelope power supply signal for RF PA circuitry

A power amplifier (PA) envelope power supply and a process to select a converter operating mode of the PA envelope power supply are disclosed. The PA envelope power supply operates in one of a first converter operating mode and a second converter operating mode. The process for selecting the converter operating mode is based on a selected communications mode of a radio frequency (RF) communications system, a target output power from RF PA circuitry of the RF communications system, and a direct current (DC) power supply voltage.

Selecting a converter operating mode of a PA envelope power supply

A power amplifier (PA) envelope power supply, which provides an envelope power supply signal to radio frequency (RF) PA circuitry, and a process to prevent undershoot of the PA envelope power supply is disclosed. The process includes determining if an envelope control signal to the PA envelope power supply has a step change from a high magnitude to a low magnitude that exceeds a step change limit. Such a step change may cause undershoot of the PA envelope power supply. As such, if the step change exceeds the step change limit, the envelope control signal is modified to use an intermediate magnitude for period of time. Otherwise, if the step change does not exceed the step change limit, the envelope control signal is not modified.

PA envelope power supply undershoot compensation

A system and method are provided for calibrating Amplitude Modulation to Phase Modulation (AM/PM) pre-distortion in a transmitter operating according to a polar modulation scheme. In general, phase modulation is disabled during transmission of an actual polar modulation signal. As a result, the transmitter provides a radio frequency (RF) output signal having an amplitude modulation component and ideally a constant phase. However, the AM/PM distortion of the transmitter creates a phase modulation component in the RF output signal. The phase component of the RF output signal, which is the AM/PM distortion of the transmitter, is measured by test equipment. The AM/PM pre-distortion applied by the transmitter is then calibrated based on the measured AM/PM distortion such that the AM/PM distortion of the transmitter is substantially reduced.

Fast calibration of AM/PM pre-distortion

A system is provided for pre-distorting a transmit signal in a mobile terminal prior to amplification by a power amplifier to compensate for AM to AM and AM to PM distortion over an input value range. Pre-distortion circuitry includes both amplitude and phase pre-distortion circuitries. The amplitude pre-distortion circuitry distorts an amplitude component of a polar transmit signal using an amplitude compensation signal that essentially cancels the AM to AM distortion, and the phase pre-distortion circuitry distorts a phase component of the polar transmit signal using a phase compensation signal that essentially cancels the AM to PM distortion. The amplitude and phase compensation signals are generated based on corresponding sets of coefficients selected from a number of sets of coefficients defining polynomials describing compensation signals for each of at least two subsets of the input value range for each of two or more power levels of the power amplifier circuitry.

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Greensboro, NC, United States of America

Brian Baxter