Envelope Tracking PA Supply Control for Low-RB Efficiency
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Solution Overview
Problem
In wireless communication devices, traditional power amplifiers with fixed supply voltage lead to significant power loss as heat due to inefficiency, especially in low-resource block transmission scenarios, where the PA operates below peak RF output power conditions.
Innovation Solution
An envelope tracking system dynamically adjusts gain compression of a power amplifier by modulating the supply voltage in response to the number of active resource blocks in a channel bandwidth, using an envelope tracking digital baseband circuit, digital-to-analog converter, and envelope tracking supply modulator circuit to generate a modulated supply voltage for the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed supply voltage is used for the power amplifier, then the circuit design is simple, but significant power loss occurs as heat especially in low-RB transmission scenarios
Solution Approach 1:
The patent implements dynamic supply voltage modulation through envelope tracking, where the PA supply voltage is dynamically adjusted according to the envelope of the RF input signal. This allows the PA to operate closer to peak efficiency conditions across varying transmission bandwidths, resolving the contradiction between simple fixed-voltage design and high power efficiency.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on the number of active resource blocks and signal envelope characteristics. By modulating the supply voltage to match the instantaneous power requirements, the system achieves high efficiency in both full-RB and low-RB scenarios without requiring complex circuit redesign.
2Loss of energy
If envelope tracking is implemented to improve PA efficiency, then power loss as heat is reduced, but the device complexity increases
Solution Approach 1:
The envelope tracking system is designed to handle multiple transmission scenarios (full-RB and low-RB) through a single unified architecture. The gain compression adjustment mechanism provides multi-functionality by adapting to different resource block configurations without requiring separate circuit implementations, thus limiting the increase in device complexity.
Solution Approach 2:
The system employs feedback mechanisms where the envelope detector monitors the RF input signal and dynamically adjusts the PA supply voltage through the ETSM circuit. This closed-loop control achieves high efficiency while keeping complexity manageable through intelligent control rather than hardware multiplication.
3Productivity
If gain compression is dynamically adjusted in response to active resource blocks, then PA efficiency is improved in low-RB cases, but the control system complexity increases
Solution Approach 1:
The system performs preliminary envelope detection and gain compression adjustment before the PA amplification stage. By pre-adjusting the supply voltage based on the detected envelope and active RB count, the PA operates at optimal efficiency points without requiring complex real-time control during amplification.
Data Source
AI summary
An envelope tracking system includes an envelope tracking digital baseband (ETDBB) circuit, a digital-to-analog converter circuit, and an envelope tracking supply modulator (ETSM) circuit. The ETDBB circuit performs envelope detection upon a transmit (TX) baseband signal to generate an envelope detection result, and generates a digital envelope input according to the envelope detection result. The digital-to-analog converter circuit converts the digital envelope input into a supply envelope signal. The ETSM circuit generates a modulated supply voltage according to the supply envelope signal, and outputs the modulated supply voltage to a power amplifier. At least one of the ETDBB circuit and the ETSM circuit dynamically adjusts gain compression (GC) of the PA in response to a number of active resource blocks (RBs) in a channel bandwidth.