An open loop envelope tracking system calibration technique and circuitry are proposed. A radio frequency power amplifier receives a modulated signal. An envelope tracker power converter generates a modulated power amplifier supply voltage for the radio frequency power amplifier based on a control signal derived from the modulated signal. A first output power and a second output power of the radio frequency power amplifier are measured when the control signal is respectively delayed by a first delay period and a second delay period. A sensitivity of the output power of the radio frequency power amplifier is near a maximum near the first delay period and the second delay period. The first delay period and/or the second delay period are adjusted until the first output power substantially equals the second output power. The first delay period and the second delay period are used to obtain a calibrated fine tuning delay offset.

Group delay calibration method for power amplifier envelope tracking

A system and method for performing sample rate conversion and creating fractional delays to a signal is disclosed. The system comprises a filter, a look up table for storing coefficients for sample rate conversion and fractional delays, and control circuitry configured to use an indexing scheme to select one or more coefficients from the look up table for rate conversion and fractional delays. The coefficients stored in the look up table comprise the coefficients required to generate delays in desired increments of a sample rate. In the disclosed method, the one or more coefficients necessary for a desired sample rate and fractional delay are selected from a single look up table and provided to a filter to delay the signal based upon the input sample rate.

Apparatuses and methods for rate conversion and fractional delay calculation using a coefficient look up table

Embodiments disclosed in the detailed description relate to a pseudo-envelope follower power management system used to manage the power delivered to a linear RF power amplifier.

Pseudo-envelope following power management system

Configuration-feedback circuitry and transceiver circuitry are disclosed. The configuration-feedback circuitry regulates an output power from a radio frequency power amplifier based on a difference between a target output power from the radio frequency power amplifier and a measured output power from the radio frequency power amplifier. The transceiver circuitry regulates a modulated power supply voltage, which is used by the radio frequency power amplifier to provide power for amplification, based on the difference between the target output power from the radio frequency power amplifier and the measured output power from the radio frequency power amplifier.

Power loop control based envelope tracking

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

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 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

This disclosure relates to adaptively reducing the peak power of harmonic distortions as a function of the operating conditions for transmission communications. Specifically, the bias of the amplifier is adaptively increased to reduce harmonic distortions when a small fraction of the resource blocks are active.

Jason Millard

Papers

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

Selecting a converter operating mode of a pa envelope power supply

Adaptive biasing to meet stringent harmonic requirements