Reconfigurable Doherty Power Amplifier for Deep Back-Off Efficiency
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Solution Overview
Problem
Existing Doherty power amplifiers face limitations in bandwidth and efficiency at deep output power back-off levels, with quadrature coupler-based solutions peaking at 6 dB of output power back-off and requiring complex gate control circuits or reduced voltage supplies.
Innovation Solution
A quadrature coupler-based Doherty power amplifier arrangement with two coupled transmission lines, where the characteristic impedance and coupling coefficient are designed to achieve efficiency peaks at deep output power back-off levels beyond 6 dB, and the efficiency is reconfigurable by adjusting the current of the auxiliary amplifier and the input impedance of the output impedance matching network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quadrature coupler-based DPA is used to improve bandwidth and efficiency, then bandwidth is extended and efficiency at power back-off is improved, but efficiency peaks only at 6 dB of output power back-off and cannot achieve deep back-off levels
Solution Approach 1:
The patent introduces a reconfigurable impedance matching network that can dynamically adjust its impedance values to optimize efficiency at different output power back-off levels. The impedance parameters are made variable rather than fixed, allowing the system to adapt to deep back-off conditions beyond the fixed 6 dB peak of conventional quadrature coupler-based DPAs.
Solution Approach 2:
The patent changes the impedance parameters of the output impedance matching network to achieve efficiency peaks at deep output power back-off levels. By adjusting the impedance values in the matching network, the system can optimize performance for different back-off conditions, moving beyond the fixed 6 dB peak limitation.
2Reliability
If gate control circuit is added to improve efficiency at deep back-off level, then efficiency is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex gate control circuit from the conventional DPA architecture. Instead of adding control circuits to manage deep back-off conditions, the invention achieves the same goal through impedance parameter adjustments in the matching network, thereby simplifying the overall device structure.
Solution Approach 2:
The patent introduces an intermediary impedance matching network that mediates between the power amplifiers and the load. This matching network serves as an intermediate component that enables efficiency optimization at deep back-off levels without requiring direct control circuits on the power amplifier gates.
3Adaptability or versatility
If reduced voltage supply is applied to main amplifier to achieve reconfigurable efficiency, then efficiency peak position is reconfigurable, but maximum output power is reduced
Solution Approach 1:
The patent changes the impedance parameters of the output matching network instead of changing the voltage supply parameters. This approach allows reconfiguration of the efficiency peak position while maintaining the original voltage supply levels and maximum output power capabilities of the main amplifier.
4Device complexity
If transmission line based DPA is used to simplify structure, then device complexity is reduced, but bandwidth is limited
Solution Approach 1:
The patent employs a composite structure combining quadrature coupler technology with reconfigurable impedance matching. This composite approach integrates the bandwidth extension capabilities of quadrature couplers with the adaptability of reconfigurable impedance networks, achieving both wide bandwidth and simplified structure without requiring multiple transmission lines.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution achieves efficiency peaks at deep output power back-off levels, offers wide bandwidth, and is reconfigurable for different power back-off levels, effectively adapting to varying peak-to-average power ratios of different modulated RF signals.
Implementation Method 1
a quadrature coupler having an input port, a through port, a coupled port and an isolated port. The quadrature coupler comprises two coupled transmission lines
Data Source
AI summary
A power amplifier arrangement (100) comprises comprising a first power amplifier (P1) and a second power amplifier (P2) of a Doherty power amplifier (110). The power amplifier arrangement (100) further comprises an input power splitter (PS), a quadrature coupler (120) comprising two coupled transmission lines (TL1/TL2) and an output impedance matching network (IMN). A current of the second power amplifier (P2) and an input impedance (RL) of the output impedance matching network (IMN) are tunable such that an efficiency of the power amplifier arrangement (100) is configurable for different output power back-off levels by changing the current of the second power amplifier (P2. Da) and the input impedance (RL) of the output impedance matching network (IMN).