Outphasing Amplifier Impedance Tuning for High-Frequency Efficiency
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Solution Overview
Problem
The impedance viewed from the amplifier to the combiner in outphasing amplifiers deviates from the optimal value due to changes in phase and frequency, degrading high frequency characteristics such as drain efficiency.
Innovation Solution
An outphasing amplifier design that includes a signal processor to adjust the phases and amplitudes of input signals to fine-tune the impedances seen from the amplifiers to impedance converters, using couplers and impedance converters to combine signals optimally, thereby maintaining high frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Chireix combiner is used to combine signals from two amplifiers, then the amplifier can achieve high output power capability, but the impedance characteristics degrade due to phase and frequency changes
Solution Approach 1:
The patent applies dynamics by making the impedance converter adjustable rather than fixed. The impedance converter's characteristics are dynamically changed based on the operating conditions (phase and frequency changes) to maintain optimal impedance matching. This allows the system to adapt to varying signal conditions while using the Chireix combiner for high power output, thereby resolving the contradiction between power capability and impedance stability.
Solution Approach 2:
The patent changes the impedance parameters of the impedance converter in response to phase and frequency variations in the amplifier outputs. By adjusting the impedance converter's parameters (such as transformation ratio or reactance) based on detected signal conditions, the system maintains proper impedance matching at the combiner input, preventing degradation of impedance characteristics while preserving the high power output capability of the Chireix configuration.
2Adaptability or versatility
If the phase and frequency of signals change during operation, then the amplifier can handle varying signal conditions, but the impedance matching deteriorates
Solution Approach 1:
The patent implements feedback by monitoring the phase and frequency of the amplifier output signals and using this information to adjust the impedance converter's characteristics. The system continuously adapts the impedance converter based on the actual signal conditions, ensuring that impedance matching is maintained even as phase and frequency vary. This closed-loop approach allows the amplifier to handle diverse signal conditions while preserving stable impedance matching.
Solution Approach 2:
The impedance converter is designed with dynamic characteristics that allow it to adjust its impedance transformation properties in real-time. This dynamic behavior enables the system to maintain proper impedance matching across varying phase and frequency conditions, resolving the contradiction between adaptability to different signal conditions and maintaining reliable impedance matching.
3Device complexity
If fixed impedance converters are used in the signal path, then the device complexity is reduced, but the high-frequency performance degrades under varying conditions
Solution Approach 1:
The patent transitions from fixed to dynamic impedance converters, allowing the converter characteristics to change based on operating conditions. This dynamic adjustment capability maintains high-frequency performance (such as drain efficiency) under varying phase and frequency conditions without requiring overly complex multi-section fixed impedance networks, thus resolving the contradiction between structural simplicity and performance reliability.
Solution Approach 2:
The impedance converter's parameters are made variable rather than fixed, allowing optimization of high-frequency characteristics under different operating conditions. This parameter adjustment capability enables the system to maintain high drain efficiency and proper impedance matching across varying signal conditions without significantly increasing device complexity, as the converter can be controlled through electronic adjustment rather than requiring multiple physical sections.
Data Source
AI summary
An outphasing amplifier includes a first amplifier, a second amplifier, a first coupler coupling a first signal and a third signal, a second coupler coupling a second signal and a fourth signal, a first impedance converter inputting the first signal coupled with the third signal, a second impedance converter inputting the second signal coupled with the fourth signal, a combiner combining the first and the second signals output from the first and the second impedance converters and outputting an output signal, and a signal processor outputting the first signal having a first phase to the first amplifier, outputting the second signal having a second phase to the second amplifier, outputting the third signal having at least one of a third phase and a first amplitude to the first coupler, and outputting the fourth signal having at least one of a fourth phase and a second amplitude to the second coupler.