Doherty Power Amplifier With 4-Port Coupler for Wider Back-Off
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Solution Overview
Problem
In 5G wireless communication systems, power amplifiers face efficiency limitations when handling high peak-to-average power ratio (PAPR) signals, leading to reduced efficiency and increased power consumption due to the need for operating in a back-off area, which is limited by existing Doherty power amplifiers.
Innovation Solution
A Doherty power amplifier is enhanced by incorporating a 4-port coupler, which includes a first and second power amplifier, a transmission line, and load impedance, allowing for the modulation of load impedance to enlarge the back-off area and improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power amplifier operates in a back-off area to linearly amplify high PAPR signals, then signal linearity is improved, but efficiency deteriorates and power consumption increases
Solution Approach 1:
The power amplifier is segmented into a main amplifier and a peaking amplifier. The main amplifier operates in Class AB mode to handle average power continuously, while the peaking amplifier operates in Class C mode to handle peak power only when needed. This segmentation allows the system to maintain high efficiency across a wider back-off area by dynamically switching between amplification modes based on signal requirements.
Solution Approach 2:
The invention implements dynamic load modulation through a variable impedance network that adjusts the load seen by the main amplifier based on the operating point. Additionally, a switching mechanism dynamically connects or disconnects the peaking amplifier depending on whether the signal exceeds a threshold level, enabling the system to adapt its efficiency characteristics to match the instantaneous signal conditions.
2Use of energy by moving object
If a Doherty power amplifier is used to enlarge the back-off area, then efficiency in back-off region is improved, but the back-off area remains limited
Solution Approach 1:
The invention changes the impedance parameters dynamically through a variable impedance network connected to the main amplifier. By adjusting the impedance value based on the operating point, the system can maintain optimal load conditions across a broader back-off range. Additionally, the peaking amplifier's contribution is modulated to change the effective back-off area, allowing the system to adapt to different signal power levels and extend the efficient operating range beyond conventional Doherty limitations.
3Use of energy by moving object
If a power amplifier operates at maximum output to improve efficiency, then power consumption is reduced, but signal linearity deteriorates for high PAPR signals
Solution Approach 1:
The power amplifier is segmented into a main amplifier operating in Class AB mode for continuous average power amplification with good linearity, and a peaking amplifier operating in Class C mode for peak power amplification with high efficiency. This segmentation allows each amplifier to operate in its optimal mode, maintaining overall signal linearity while improving efficiency.
Solution Approach 2:
The switching between main amplifier and peaking amplifier operation occurs periodically based on the signal envelope detection. When the signal exceeds a threshold, the peaking amplifier is activated; when it remains below the threshold, only the main amplifier operates. This periodic switching action enables the system to maintain linearity for high PAPR signals while achieving higher average efficiency.
Data Source
AI summary
The disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long-Term Evolution (LTE). A Doherty power amplifier of a wireless communication system is provided. The Doherty power amplifier includes a first power amplifier, a second power amplifier, a first transmission line, a 4-port coupler, and a load impedance, and the 4-port coupler includes a first port, a second port, a third port, and a fourth port, the first power amplifier is coupled with the 4-port coupler through the first port, the second power amplifier is coupled with the 4-port coupler through the fourth port, the load impedance is coupled with the 4-port coupler through the third port, the first transmission line is disposed between the first power amplifier and the first port of the 4-port coupler, and the second port is an output end of the power amplifier.