Shared Envelope Tracking for MIMO Power Amplifier Efficiency
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Solution Overview
Problem
In MIMO systems, the existing envelope tracking modulated power supply arrangements for multiple power amplifiers increase overhead due to the need for separate modulators for each amplifier, and they struggle to efficiently manage different input signals with varying envelopes, leading to inefficiencies and distortion.
Innovation Solution
A common envelope tracking modulator generates a power supply voltage based on the highest instantaneous envelope signal across multiple power amplifiers, using an envelope selector and moving average filter to ensure sufficient voltage and adaptive pre-distortion correction, with feedback from power amplifier outputs to adjust pre-distortion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If separate envelope tracking modulators are provided for each power amplifier in a MIMO system, then each amplifier can be efficiently supplied with its own modulated power supply voltage tracking its input signal envelope, but the overhead and device complexity of the transmitter increases significantly
Solution Approach 1:
The patent combines multiple separate envelope tracking modulators into a single shared modulator that serves multiple power amplifiers. The modulator generates a common modulated power supply voltage that is distributed to multiple amplifiers, reducing the number of modulator stages from N (one per amplifier) to 1, thereby reducing device complexity and overhead while maintaining efficiency benefits
Solution Approach 2:
The single envelope tracking modulator is designed to serve multiple power amplifiers simultaneously, making it a universal component that performs the envelope tracking function for the entire MIMO transmitter rather than being dedicated to a single amplifier. This multi-functional approach reduces overall system complexity
2Device complexity
If a common envelope tracking modulator is used for multiple power amplifiers, then overhead is reduced, but the modulator must handle multiple different input signal envelopes which complicates the envelope selection and voltage tracking process
Solution Approach 1:
The patent segments the envelope processing function by introducing an envelope selector that receives multiple input envelopes and selects the maximum envelope signal. This segmentation separates the envelope tracking function into distinct stages: envelope extraction from multiple inputs, maximum envelope selection, and modulated voltage generation, making the system manageable despite handling multiple inputs
Solution Approach 2:
The system employs feedback mechanisms where the selected maximum envelope signal is used to control the common modulator, and the modulator's output is monitored to ensure proper tracking. This feedback allows the system to adapt to varying input conditions and maintain optimal performance across different signal scenarios
3Use of energy by moving object
If the power supply voltage is optimized for one amplifier's envelope, then that amplifier achieves maximum efficiency, but other amplifiers with different envelope requirements may not receive sufficient voltage, leading to distortion or performance degradation
Solution Approach 1:
The system dynamically adapts the power supply voltage by continuously selecting the maximum envelope signal from multiple inputs. This dynamic approach ensures that the modulated power supply voltage automatically adjusts to meet the highest demand among all amplifiers at any given time, maintaining both efficiency and signal quality across all channels
Solution Approach 2:
The system changes the parameter of power supply voltage based on the selected envelope signal. By monitoring and responding to envelope variations in real-time, the system optimizes the voltage parameter to satisfy all amplifiers' requirements while maintaining overall system efficiency
Data Source
AI summary
There is disclosed an amplifier arrangement comprising a plurality of amplifiers each arranged to amplify one of a plurality of different input signals, the arrangement comprising an envelope tracking modulator for generating a common power supply voltage for the power amplifiers, and further comprising an envelope selector adapted to receive a plurality of signals representing the envelopes of the plurality of input signals, and adapted to generate an output envelope signal representing the one of the plurality of envelopes having the highest level at a particular time instant as the input signal for the envelope tracking modulator.