Envelope-Controlled Doherty Amplifier Bias for High-PAPR Efficiency
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Solution Overview
Problem
Current power amplifiers in RF communication systems face inefficiencies, particularly at low signal power levels, leading to reduced battery life and increased power consumption, as they operate at inefficient operating points when amplifying signals with high peak-to-average power ratio (PAPR) waveforms.
Innovation Solution
A Doherty power amplifier system with an input splitting circuit, main and auxiliary amplifiers, and a bias circuit that controls the state of the amplifiers based on an envelope signal, allowing for efficient operation by selectively enabling or disabling the auxiliary amplifiers depending on the signal power level, thereby optimizing power usage and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power amplifiers operate continuously at high power levels to handle high PAPR waveforms, then signal coverage and transmission reliability are improved, but power consumption increases and battery life decreases
Solution Approach 1:
The patent implements dynamic operation of power amplifiers by selectively enabling and disabling auxiliary amplifiers based on instantaneous signal power levels. The main amplifier operates continuously while auxiliary amplifiers are activated only when needed, transforming the static high-power operation into a dynamic state that adapts to signal conditions, thereby reducing average power consumption while maintaining transmission reliability.
Solution Approach 2:
The power amplifier system is segmented into a main amplifier and multiple auxiliary amplifiers that operate independently. This segmentation allows the system to activate only the necessary amplifier components based on signal requirements, avoiding the need to operate all amplifiers at full power continuously, thus reducing overall power consumption while maintaining adequate signal coverage.
2Power
If power amplifiers are designed to handle peak power levels efficiently, then high PAPR waveform amplification is improved, but efficiency at low power levels deteriorates
Solution Approach 1:
The amplifier system is divided into a main amplifier optimized for continuous operation and auxiliary amplifiers optimized for peak power handling. During low power periods, only the efficient main amplifier operates. During peak power periods, auxiliary amplifiers are activated to provide the additional power handling capability, ensuring both peak power performance and low-power efficiency are optimized separately.
Solution Approach 2:
The system uses the envelope signal of the input waveform to automatically control the activation of auxiliary amplifiers. When the envelope indicates high power levels, auxiliary amplifiers are enabled; when low, they are disabled. This self-service mechanism ensures optimal efficiency across varying power levels without external intervention.
3Power
If multiple auxiliary amplifiers are used to improve power handling, then power capacity is increased, but system complexity increases
Solution Approach 1:
Multiple auxiliary amplifiers are merged into a unified control structure where a single envelope signal controls the activation of all auxiliary amplifiers. This merging approach allows the system to manage multiple amplifiers through a common control mechanism, reducing the complexity that would otherwise arise from managing each amplifier independently while still providing the power handling capacity of multiple units.
4Loss of energy
If envelope tracking systems are implemented to achieve high efficiency, then power efficiency is improved, but system complexity and cost increase
Solution Approach 1:
The system implements a simplified form of envelope tracking by using the envelope signal dynamically to control amplifier activation states rather than continuously adjusting supply voltages. This dynamic state control achieves similar efficiency benefits to full envelope tracking but with reduced complexity by avoiding voltage regulation circuits and continuous analog control, using instead discrete enable/disable control based on envelope thresholds.
Data Source
AI summary
Doherty power amplifier systems with envelope controlled state are provided herein. In certain embodiments, a Doherty power amplifier system includes a main amplifier, a first auxiliary amplifier, and a second auxiliary amplifier that operate in combination with one another to amplify an RF signal. The Doherty power amplifier system further includes a bias circuit that biases the first and second auxiliary amplifiers based on an envelope of the RF signal to control a state of the Doherty power amplifier system. For example, in certain implementations, the first and second auxiliary amplifiers are selectively activated based on a power level indicating by the envelope.