Multi-Mode Envelope Tracking Voltage Circuit for 5G rIMD Suppression
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Solution Overview
Problem
5G-NR power amplifiers face efficiency and performance degradation due to reverse intermodulation products (rIMD) when operating in standalone (SA) or non-standalone (NSA) modes, leading to increased power consumption and thermal dissipation.
Innovation Solution
A multi-mode envelope tracking (ET) target voltage circuit is implemented, utilizing lower- and higher-slope look-up tables to generate ET target voltages based on reduced and increased slew rates, respectively, to suppress rIMD and enhance amplifier efficiency and performance in both SA and NSA modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the amplifier circuit operates in 5G SA or NSA mode with conventional ET target voltage, then the amplifier can provide high output power, but reverse intermodulation products (rIMD) are generated that degrade efficiency and performance
Solution Approach 1:
The patent changes the slew rate parameter of the ET target voltage by selecting between different look-up tables (lower-slope LUT for SA/NSA mode, higher-slope LUT for other modes). This parameter modification suppresses rIMD generation while maintaining the required output power levels for 5G operation.
Solution Approach 2:
The system dynamically switches between different look-up tables based on the operating mode (SA/NSA vs. other modes). The target voltage control circuit selects the appropriate LUT in real-time, allowing the amplifier to adapt its ET target voltage characteristics to the specific operational requirements and minimize rIMD.
2Speed
If the ET target voltage uses higher slew rate, then the amplifier responds faster to power envelope changes, but rIMD increases degrading efficiency
Solution Approach 1:
The patent modifies the slew rate parameter by selecting between lower-slope and higher-slope look-up tables. For 5G SA/NSA modes, the lower-slope LUT is used to reduce rIMD and improve efficiency, while the higher-slope LUT is used in other modes where faster response is prioritized over efficiency.
Solution Approach 2:
Different slew rate characteristics are applied locally to different operating modes. The system uses conditional logic to select the appropriate LUT based on the current mode, applying the optimal slew rate characteristic (lower for SA/NSA, higher for others) to each specific operational context.
3Device complexity
If a single look-up table is used for ET target voltage generation, then the circuit design is simpler, but the amplifier cannot efficiently adapt to different operating modes (SA, NSA, and other modes)
Solution Approach 1:
The patent segments the look-up table into two separate tables: a lower-slope LUT for 5G SA/NSA modes and a higher-slope LUT for other modes. This segmentation allows each table to be optimized for its specific operational context, improving adaptability while keeping the overall structure manageable through clear separation of functions.
Solution Approach 2:
The target voltage control circuit is designed with multi-functionality, capable of selecting between different look-up tables based on the operating mode. This universal design allows the same circuit to efficiently handle multiple operational scenarios (5G SA, 5G NSA, and other modes) by dynamically switching between the appropriate LUT.
Data Source
AI summary
A multi-mode envelope tracking (ET) target voltage circuit is provided. In an ET amplifier apparatus, an amplifier circuit is configured to amplify a radio frequency (RF) signal based on a time-variant ET voltage, which is generated based on a time-variant ET target voltage configured to track a time-variant power envelope of the RF signal. Notably, when the ET amplifier apparatus operates in a fifth-generation (5G) standalone (SA) or non-standalone (NSA) mode, the amplifier circuit may experience interference creating a reverse intermodulation product (rIMD) that can degrade efficiency and performance of the amplifier circuit. In examples discussed herein, the multi-mode ET target voltage circuit is configured to generate the ET target voltage based on a reduced slew rate to help suppress the rIMD at the amplifier circuit, thus making it possible to improve efficiency and performance of the ET amplifier apparatus in the SA and the NSA modes.