Envelope Tracking PA Control for VSWR-Driven EVM Stability
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Solution Overview
Problem
Envelope tracking power amplifiers in mobile communication devices face challenges in maintaining error vector magnitude (EVM) thresholds due to dynamic changes in voltage standing wave ratio (VSWR) caused by wide modulation bandwidth and various phase angles, leading to inefficiencies and increased power consumption.
Innovation Solution
An ET power amplifier apparatus with a control circuit that dynamically determines VSWR changes and adjusts the ET voltage to maintain the required EVM threshold across all phase angles, using a tracker circuit to generate ET voltage based on an ET target voltage and an amplifier circuit to amplify RF signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope tracking is used to improve PA efficiency, then power consumption and thermal dissipation are reduced, but dynamic VSWR changes cause the amplifier to fail EVM requirements
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors VSWR at the voltage output and dynamically adjusts the ET target voltage in response to VSWR changes. This closed-loop feedback ensures that the amplifier maintains EVM compliance while operating under envelope tracking, resolving the contradiction between power efficiency and EVM requirement compliance.
Solution Approach 2:
The system transitions from a static ET target voltage to a dynamic adjustment mechanism. The control circuit dynamically determines VSWR changes and causes corresponding adjustments to the ET target voltage, allowing the system to adapt to varying load conditions while maintaining both efficiency and EVM compliance.
2Productivity
If the amplifier operates at higher output power to achieve higher data rates, then wireless communication performance is improved, but power consumption and thermal dissipation increase
Solution Approach 1:
The patent changes the operating parameters of the power amplifier by dynamically adjusting the ET target voltage based on VSWR conditions. This allows the amplifier to operate at higher output powers when needed for high data rates while maintaining optimal efficiency through adaptive parameter control, thus resolving the contradiction between productivity and energy consumption.
3Reliability
If the ET target voltage is increased to maintain EVM threshold under VSWR changes, then EVM compliance is improved, but power consumption increases
Solution Approach 1:
Rather than using a static high ET target voltage, the system dynamically adjusts the ET target voltage only when VSWR changes occur. This dynamic approach maintains EVM compliance during critical conditions while avoiding unnecessary power consumption during normal operation, resolving the contradiction between reliability and energy use.
Solution Approach 2:
The system applies ET target voltage adjustment selectively and partially - only when VSWR changes are detected and only to the extent necessary to maintain EVM compliance. This avoids the excessive action of continuously maintaining a high ET target voltage, thus reducing power consumption while still ensuring EVM threshold compliance when needed.
Data Source
AI summary
An envelope tracking (ET) power amplifier apparatus is provided. The ET power amplifier apparatus includes an amplifier circuit configured to amplify a radio frequency (RF) signal based on an ET voltage and a tracker circuit configured to generate the ET voltage based on an ET target voltage. The ET power amplifier apparatus also includes a control circuit. The control circuit is configured to dynamically determine a voltage standing wave ratio (VSWR) change at a voltage output relative to a nominal VSWR and cause an adjustment to the ET voltage. By dynamically determining the VSWR change and adjusting the ET voltage in response to the VSWR change, the amplifier circuit can operate under a required EVM threshold across all phase angles of the RF signal.