Dual-Output Supply Modulator for Two-Stage PA Efficiency
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Solution Overview
Problem
Two-stage power amplifiers in wireless communication systems face efficiency issues due to the lower efficiency of auxiliary amplification stages and increased circuit complexity from adding DC/DC converters for stable power supply, especially when using traditional envelope tracking modulators.
Innovation Solution
A dual-output and dual-mode supply modulator that simultaneously supplies an envelope tracking signal to the main amplification stage and an average power tracking signal to the auxiliary amplification stage in high output power regions, and employs average power tracking on both stages in low output power regions, using a single supply modulator to improve efficiency and simplify the circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional envelope tracking supply modulator is used to improve the efficiency of the main amplification stage, then the efficiency of the main amplification stage is improved, but a DC/DC converter needs to be added to provide stable power supply to the auxiliary amplification stage, which increases the circuit size and complexity
Solution Approach 1:
The patent combines the power supply functions for both the main amplification stage and auxiliary amplification stage into a single supply modulator. The supply modulator generates multiple output voltages (first output voltage for main stage, second output voltage for auxiliary stage) without requiring separate DC/DC converters, thereby reducing circuit complexity while maintaining efficiency improvements for both stages.
Solution Approach 2:
The supply modulator is designed to perform multiple functions: it provides envelope tracking for the main amplification stage to improve its efficiency, simultaneously provides stable power supply to the auxiliary amplification stage, and can operate in different modes (first mode and second mode) to adapt to different operating conditions. This multi-functionality eliminates the need for additional dedicated DC/DC converters.
2Manufacturing precision
If the power amplifier operates in a back-off region to linearly amplify high PAPR modulated signals, then linearity is improved, but the efficiency of the power amplifier is much lower compared to when it operates in the maximum output region
Solution Approach 1:
The supply modulator dynamically adjusts the output voltages based on the operating mode and signal conditions. In the first mode, it provides envelope tracking voltage to the main amplification stage to improve efficiency while maintaining linearity in the back-off region. The dynamic switching between first mode and second mode allows the system to optimize the balance between linearity and efficiency depending on the operating conditions.
Solution Approach 2:
The patent changes the supply voltage parameters dynamically through envelope tracking and mode switching. By modulating the supply voltage to follow the envelope of the input signal and switching between different operating modes, the power amplifier can maintain high linearity in the back-off region while significantly improving efficiency compared to fixed supply voltage operation.
3Power
If an auxiliary amplification stage is added to achieve high gain, then the gain requirement is met, but the auxiliary amplification stage has much lower efficiency than the main amplification stage, resulting in a decrease in the efficiency of the overall transmission system
Solution Approach 1:
The supply modulator provides differentiated power supply to different stages: it applies envelope tracking to the main amplification stage for high efficiency and applies stable voltage supply to the auxiliary amplification stage. This localized optimization allows each stage to operate in its most efficient mode while achieving the required overall gain, thereby improving the efficiency of the auxiliary stage without compromising the gain requirement.
Data Source
AI summary
A dual-output and dual-mode supply modulator, a two-stage power amplifier using the same, and a supply modulation method therefor are provided. In order to improve the performance of a two-stage power amplifier used in a transmitter of a wireless communication system, the dual-output and dual-mode supply modulator according to the present invention may simultaneously supply an envelope tracking signal to a main amplification stage of the two-stage power amplifier and an average power tracking signal to an auxiliary amplification stage thereof. To this end, the dual-output and dual-mode supply modulator according to the present invention outputs two supply voltages and supports two operation modes. As such, it is possible to improve the efficiency of the two-stage power amplifier over a wide output power range with the use of a single supply modulator by employing envelope tracking on the main amplification stage and average power tracking on the auxiliary amplification stage in high output power regions or employing average power tracking both on the main amplification stage and auxiliary amplification stage in low output power regions.