Doherty Power Amplifier With Envelope Tracking Under Power Back-Off
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Solution Overview
Problem
Power amplifiers in base stations face efficiency losses when amplifying signals with high peak-to-average ratios, particularly when using power back-off methods, leading to increased energy consumption and limited improvement in power amplification efficiency.
Innovation Solution
A power amplifier configuration that includes an envelope modulator connected to both the main and auxiliary power amplifiers, using the envelope voltage as operating voltage, allowing for simultaneous adjustment and improving symmetry, thereby leveraging the efficiency advantage of Doherty amplifiers under power back-off and combining it with envelope tracking technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power back-off method is used to amplify signals with high peak-to-average ratio, then linearity of power amplifier is improved, but power amplification efficiency dramatically decreases
Solution Approach 1:
The power amplifier is divided into a main power amplifier and an auxiliary power amplifier. The main power amplifier handles the carrier signal while the auxiliary power amplifier handles the envelope signal, allowing each component to operate in its optimal efficiency region while maintaining overall linearity through their combined operation.
Solution Approach 2:
The patent implements dynamic envelope tracking by using an envelope modulator to generate a time-varying envelope voltage that dynamically adjusts the operating voltage of the main power amplifier according to the instantaneous envelope of the input signal. This dynamic adjustment allows the power amplifier to maintain high efficiency across varying signal conditions while preserving linearity.
2Use of energy by moving object
If Doherty amplifier with envelope modulator is used, then power amplification efficiency is improved under back off, but loss of power amplification efficiency is easily caused
Solution Approach 1:
The patent applies different operating conditions to different parts of the system: the main power amplifier operates in a saturated or near-saturated mode for high efficiency, while the auxiliary power amplifier operates in a linear region to provide envelope tracking. The envelope modulator separately controls the gate and drain voltages of each amplifier, allowing localized optimization of each component's operating characteristics.
Solution Approach 2:
The envelope modulator continuously monitors the envelope signal and dynamically adjusts the operating voltages of both power amplifiers in real-time based on the instantaneous signal conditions. This feedback mechanism ensures that the amplifiers maintain optimal efficiency while preventing efficiency loss under varying operating conditions.
3Reliability
If power amplifier operates in linear region away from saturation, then linearity is improved, but energy consumption is increased greatly
Solution Approach 1:
The power amplifier system is segmented into two independent amplification paths: one for the carrier signal and one for the envelope signal. This segmentation allows the carrier amplifier to operate efficiently in saturation while the envelope amplifier maintains linearity, achieving both low energy consumption and high linearity simultaneously.
Solution Approach 2:
The patent changes the operating parameters dynamically by using envelope tracking to adjust the supply voltage of the main power amplifier according to the instantaneous envelope of the input signal. This parameter change allows the amplifier to operate at lower voltages during low-power conditions, reducing energy consumption while maintaining linearity when needed.
Data Source
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AI summary
Embodiments of the present invention provide a power amplifier, a radio remote unit RRU, and a base station. The power amplifier includes: an envelope controller, a main power amplifier, and an auxiliary power amplifier. The main power amplifier and the auxiliary power amplifier both use an envelope voltage output by the envelope modulator as operating voltages, and because the operating voltages of the main power amplifier and the auxiliary power amplifier may be adjusted simultaneously, symmetry of the power amplifier is improved, and there is a low probability that an efficiency loss occurs, thereby enhancing efficiency of the power amplifier.