PA Gain Compression Control by Resource-Block-Aware Envelope Tracking
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Solution Overview
Problem
Traditional power amplifiers in wireless communication devices operate inefficiently due to fixed supply voltage, leading to significant power loss as heat, especially when the number of active resource blocks in the channel bandwidth is low, which affects efficiency in 4G-LTE/5G-NR wireless communications.
Innovation Solution
An envelope tracking system that dynamically adjusts gain compression of a power amplifier by modulating the supply voltage in response to the number of active resource blocks, utilizing an envelope tracking digital baseband circuit, digital-to-analog converter circuit, and envelope tracking supply modulator circuit to generate a modulated supply voltage, thereby optimizing power usage.
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 the power amplifier operates inefficiently and dissipates significant power as heat
Solution Approach 1:
The patent implements dynamic supply voltage modulation through envelope tracking, where the PA supply voltage is dynamically adjusted to follow the envelope of the RF input signal. This transforms the static fixed-voltage system into a dynamic system that adapts to signal conditions, improving power efficiency by keeping the PA operating closer to its peak efficiency point while maintaining simplicity through dedicated envelope tracking circuitry.
2Loss of energy
If envelope tracking is implemented to improve power efficiency, then power dissipation is reduced, but the system complexity increases
Solution Approach 1:
The patent segments the power amplifier system into distinct functional blocks: the PA itself, the envelope detector that extracts the signal envelope, the supply modulator that generates the modulated supply voltage, and the envelope follower circuit. This segmentation allows each component to be optimized independently and simplifies the overall design by distributing complexity across specialized modules rather than requiring a completely redesigned integrated system.
3Productivity
If the channel bandwidth is wide with many resource blocks, then the transmission capacity is high, but the power amplifier gain compression increases
Solution Approach 1:
The patent dynamically changes the supply voltage parameter of the power amplifier based on the envelope of the input signal and the number of active resource blocks. By adjusting the supply voltage in real-time, the system maintains optimal PA operating conditions across different transmission scenarios, preventing excessive gain compression when wide bandwidths are used while preserving high transmission capacity.
Data Source
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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.