Dual-Drive Doherty Power Amplifier for Load-Modulated Efficiency
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Solution Overview
Problem
Conventional power amplifiers suffer from limited efficiency, output power, and gain due to low devices breakdown voltages, limited fmax, poor quality on chip passives, and limited voltage swing, especially when operating under complex modulation schemes like QAMs/OFDM, leading to reduced average modulation efficiency.
Innovation Solution
A dual-drive Doherty power amplifier architecture combining a Doherty load modulation power combining network with main/auxiliary PA cores, utilizing a dual-drive configuration that actively modulates the load and couples the gate and source terminals of a differential pair out-of-phase, enhancing voltage swing and reducing input impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional power amplifiers operate under complex modulation schemes like QAMs/OFDM, then signal complexity and data rate are improved, but average modulation efficiency deteriorates due to low peak operating probability
Solution Approach 1:
The patent implements dynamic load modulation where the load impedance seen by the main amplifier is dynamically adjusted based on the power level. The Doherty network modifies the load conditions in real-time to maintain high efficiency across varying signal envelopes, allowing the amplifier to operate efficiently whether at peak or lower power levels during complex modulation cycles.
Solution Approach 2:
The patent divides the power amplification function into two separate amplifiers (main and auxiliary) that operate in parallel but with different functions. The main amplifier handles continuous operation while the auxiliary amplifier supplements during peak demands, allowing each to be optimized for specific operating conditions and improving overall average efficiency.
2Loss of energy
If Doherty amplifier uses dynamic load modulation to boost efficiency at lower power levels, then average efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines the main and auxiliary power amplifiers into a unified Doherty amplifier system with integrated load modulation functionality. By merging these components into a single coordinated system rather than separate independent amplifiers, the patent achieves high average efficiency while managing complexity through functional integration.
Solution Approach 2:
The Doherty network serves multiple functions simultaneously: it acts as a power combining network, a load modulation mechanism, and an impedance transformation system. This multi-functionality reduces the need for additional separate components, thereby achieving improved efficiency without proportionally increasing device complexity.
3Power
If dual-drive configuration couples gate and source terminals out-of-phase, then voltage swing and peak efficiency are improved, but input impedance decreases requiring matching networks
Solution Approach 1:
The patent incorporates impedance matching networks as integral parts of the dual-drive amplifier design from the outset, rather than as afterthoughts. The matching networks are pre-designed and integrated into the amplifier structure to handle the reduced input impedance, eliminating the need for additional external matching components and reducing overall system complexity.
Data Source
AI summary
Provided is a dual-drive based Doherty amplifier that includes a first power amplifier and a second power amplifier that is in parallel with the first power amplifier. The first power amplifier is configured to receive a first portion of a signal having a first phase, and the second power amplifier is configured to receive a second portion of the signal having a second phase that has a phase difference from the first phase. At least one of the first power amplifier or the second power amplifier includes a dual-drive power amplifier core.