Outphasing Amplifier Combiner With Open Stubs for Back-Off Efficiency
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Solution Overview
Problem
Outphasing amplifiers are typically large due to the inclusion of harmonic circuits, which increases their size and affects efficiency.
Innovation Solution
The outphasing amplifier design incorporates a Chireix combiner with specific impedance converters and open stubs, where the electrical lengths of these components are optimized to minimize size and improve efficiency by adjusting the outphasing angle to achieve better impedance matching and reduced reactance components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If harmonic circuits are included in the outphasing amplifier, then the amplifier can process high-frequency signals effectively, but the size of the amplifier increases
Solution Approach 1:
The patent extracts and removes the harmonic circuits from the outphasing amplifier configuration. By eliminating these circuits while maintaining the core outphasing functionality through optimized impedance converters and open stubs, the amplifier achieves high-frequency signal processing capability without the size penalty of including harmonic circuits.
2Loss of energy
If the electrical length of open stubs is optimized for impedance matching, then amplifier efficiency is improved, but the design complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the electrical lengths of the open stubs to specific values (θ3 and θ4) that differ from conventional designs. This parameter optimization achieves improved impedance matching and amplifier efficiency, particularly at back-off power settings, while the manufacturing method simplifies the implementation by providing clear guidelines for the stub length adjustments.
3Reliability
If outphasing angle is adjusted to optimize impedance matching, then amplifier characteristics are improved, but the device requires more complex control mechanisms
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the electrical lengths of the open stubs during the manufacturing process. This preliminary configuration of the impedance converters and stubs establishes the optimal outphasing angle characteristics in advance, eliminating the need for complex real-time control mechanisms while maintaining improved amplifier characteristics.
Data Source
AI summary
An outphasing amplifier includes a first amplifier, a second amplifier, and a combiner. The combiner includes a first node inputting a first signal, a second node inputting a second signal, a third node outputting a combined signal as an output signal, a first impedance converter connected to the first node and the third node, a second impedance converter connected to the second node and the third node, a first open stub wherein when an electrical length converted into a phase at a center frequency of an operating frequency band is θ3, and an outphasing angle when a power of the output signal has a minimum value is θbo, θ3 is different from 180°−θbo and +θbo, and a second open stub wherein when an electrical length converted into a phase at the center frequency is θ4, θ4 is different from 180°−θbo and +θbo.