Multi-PA Envelope Tracking for Higher RF Power Efficiency
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Solution Overview
Problem
Power amplifiers in RF communication systems face challenges in efficiently managing RF signal power, leading to reduced battery life and suboptimal transmit power levels, particularly in devices like mobile phones and base stations that require efficient power management for multiple carrier aggregations and frequency bands.
Innovation Solution
An envelope tracking system is implemented, which includes a power amplifier and an envelope tracker with a multi-level switching circuit that generates an output current based on the envelope signal of the RF transmit signal, combining it with a DC voltage to produce a supply voltage for the power amplifier, using a combiner with inductors and capacitors for voltage adjustment, and a sigma-delta encoder for noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power amplifier is used to amplify RF signals for transmission, then the transmit power level is increased, but the power consumption increases and battery life is reduced
Solution Approach 1:
The patent implements dynamic supply voltage adjustment by tracking the envelope of the RF signal. The supply voltage to the power amplifier is dynamically varied according to the instantaneous power level of the RF signal, allowing the amplifier to operate efficiently across different power levels rather than at a fixed high voltage, thus reducing overall power consumption while maintaining required transmit power levels
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on the RF signal envelope. By adjusting the supply voltage to match the instantaneous power requirements of the amplifier, the system achieves better power efficiency - the voltage is increased only when needed for high power transmission and reduced during low power periods, directly addressing the contradiction between transmit power and power consumption
2Loss of energy
If the power amplifier supply voltage is dynamically adjusted to improve efficiency, then power added efficiency is enhanced, but the system complexity increases
Solution Approach 1:
The patent introduces an envelope tracker as an intermediary component between the RF signal source and the power amplifier. This tracker extracts the envelope information from the RF signal and uses it to control the supply voltage, thereby implementing efficiency improvements without requiring direct modification of the power amplifier itself. The intermediary handles the complexity of dynamic voltage control separately
Solution Approach 2:
The system is segmented into distinct functional blocks: the RF signal path and the supply voltage control path. The envelope tracker processes the RF signal envelope separately to generate control signals for the supply voltage modulation. This segmentation allows the efficiency enhancement mechanism to be implemented independently from the main RF amplification function, reducing overall system complexity
3Productivity
If multiple power amplifiers are used for carrier aggregation, then the bandwidth and data rate are increased, but the power management complexity increases
Solution Approach 1:
The envelope tracker is designed with multi-functionality to support multiple power amplifiers simultaneously. A single envelope tracker can process envelope signals from multiple RF inputs and generate corresponding supply voltage controls for multiple amplifiers, reducing the need for separate control circuits for each amplifier and thereby managing power complexity efficiently across multiple carriers
Solution Approach 2:
The patent combines the power management functions for multiple amplifiers into a unified envelope tracking system. By merging the envelope detection and voltage control functions, the system achieves coordinated power management across multiple carriers and amplifiers, simplifying the overall power management architecture while supporting increased bandwidth through carrier aggregation
Data Source
AI summary
Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker system includes a first power amplifier that amplifies a first radio frequency (RF) signal and receives power from a first supply voltage, a second power amplifier that amplifies a second RF signal and receives power from a second supply voltage, and an envelope tracker including a first modulator that generates a first output current based on an envelope of the first RF signal and a plurality of regulated voltages, a second modulator that generates a second output current based on an envelope of the second RF signal and the regulated voltages, a first combiner that combines a first DC voltage with the first output current to generate the first supply voltage, and a second combiner that combines a second DC voltage with the second output current to generate the second supply voltage.