Intra-symbol Voltage Modulation for RF Power Amplifier Efficiency
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Solution Overview
Problem
In 5G-NR wireless communication systems, the power amplifier circuit faces challenges in adapting to the time-variant power of RF signals within each OFDM symbol duration, leading to inefficiencies and potential distortion such as amplitude clipping.
Innovation Solution
The implementation of intra-symbol voltage modulation, where the voltage modulation interval is divided into multiple subintervals, allows for the adaptation of the modulated voltage to better track the time-variant input power of the RF signal. This is achieved through a target voltage processing circuit that determines respective voltage targets for each subinterval, enabling more frequent adjustments to the modulated voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage modulation is updated only at the beginning of each OFDM symbol, then the circuit complexity is reduced, but the modulated voltage cannot track the time-variant input power within the symbol, leading to distortion and reduced efficiency
Solution Approach 1:
The OFDM symbol duration is divided into multiple voltage modulation subintervals (e.g., first subinterval, second subinterval, third subinterval). The modulated voltage is updated at the beginning of each subinterval rather than only at the symbol level. This segmentation allows the voltage to track time-variant input power more accurately while keeping the update frequency manageable, thus resolving the contradiction between tracking accuracy and circuit complexity.
2Productivity
If the modulation bandwidth is increased to achieve higher data rates, then the productivity is improved, but the OFDM symbol duration becomes shorter, making it more difficult to adapt the modulated voltage within the symbol
Solution Approach 1:
By segmenting the voltage modulation interval into multiple subintervals, the system can maintain accurate voltage tracking even when the overall OFDM symbol duration is short. Each subinterval provides a dedicated time window for voltage updates, ensuring that the power amplifier can adapt to input power variations regardless of the compressed symbol duration caused by high modulation bandwidths.
Solution Approach 2:
The system dynamically adjusts the modulated voltage at multiple points within each OFDM symbol based on the instantaneous input power conditions. This dynamic updating approach allows the voltage to adapt to changing power requirements throughout the symbol duration, which is particularly important when symbols are shortened due to high data rate requirements.
Data Source
AI summary
Intra-symbol voltage modulation in a wireless communication circuit is disclosed. In a wireless communication circuit, a power amplifier circuit is configured to amplify a radio frequency (RF) signal based on a modulated voltage that tracks a time-variant input power of the RF signal. Herein, intra-symbol voltage modulation means that the modulated voltage can be adapted within a voltage modulation interval(s), such as an orthogonal frequency division multiplexing (OFDM) symbol duration. In embodiments disclosed herein, the voltage modulation interval(s) is divided into multiple voltage modulation subintervals and a respective voltage target is determined for each of the voltage modulation subintervals. Accordingly, the modulated voltage can be adapted in each of the voltage modulation subintervals according to the respective voltage target. By performing intra-symbol voltage modulation during the voltage modulation interval(s), the power amplifier circuit can operate with higher efficiency and prevent distortion (e.g., amplitude clipping) when amplifying the RF signal.