Digital Multistage RF Combiner for High-PAPR Amplifier Efficiency
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Solution Overview
Problem
Existing power combining techniques for parallel amplifier structures face efficiency losses due to reactive loading and interactions between amplifiers, especially when handling signals with high peak-to-average power ratio (PAPR), leading to reduced amplification efficiency in wireless communication systems.
Innovation Solution
A digitally controlled multistage power combining structure that activates and deactivates combiners and amplifier outputs based on digital control information, ensuring lossless signal combination by selecting input signals according to power and phase values, using a digital combiner controller circuit and phase amplifier controller to manage switches and phases for optimal power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power combining techniques are used for parallel amplifier structures, then output power is increased, but efficiency losses occur due to reactive loading and interactions between amplifiers
Solution Approach 1:
The invention segments the power combining process into multiple stages, where each stage combines a subset of amplifier outputs. This segmentation isolates the amplifiers from each other's reactive loading effects while still achieving power combining, thereby maintaining efficiency while increasing output power capability.
Solution Approach 2:
The invention dynamically controls the activation and deactivation of individual amplifiers and combiner stages based on the input signal's envelope level. By adapting which amplifiers are active at any given moment, the system avoids the efficiency losses that would occur from continuous operation of all amplifiers under varying load conditions.
2Reliability
If amplifiers operate with high PAPR signals, then signal fidelity is maintained, but amplification efficiency is reduced due to back-off requirements
Solution Approach 1:
The invention changes the operating parameters of the amplifiers dynamically based on the signal envelope level. By adjusting which amplifiers are active and at what power level based on the instantaneous envelope, the system maintains signal fidelity for high PAPR signals while operating amplifiers at optimal efficiency points rather than requiring continuous back-off.
Solution Approach 2:
The invention uses partial action by activating only the necessary number of amplifiers based on the current signal power requirements. Instead of operating all amplifiers at reduced power (back-off), the system activates only enough amplifiers to handle the current envelope level, thereby improving overall efficiency while maintaining signal fidelity.
3Adaptability or versatility
If multiple amplifiers with different output powers are used, then power combining flexibility is increased, but device complexity increases
Solution Approach 1:
The invention segments the multiple amplifiers into hierarchical groups that feed into different stages of the combiner structure. This segmentation organizes the complexity into manageable sections, where each stage handles a specific subset of amplifiers, making the control logic more systematic and less complex than a fully interconnected system.
Solution Approach 2:
The invention performs preliminary organization of amplifiers into fixed groups with predetermined power relationships before the combining process. This preliminary structuring simplifies the real-time control decisions, as the system only needs to select which pre-organized groups to activate rather than making complex real-time assignments, thereby reducing control complexity while maintaining flexibility.
Data Source
AI summary
Circuits and methods for using in parallel amplification and signal combining are described herein. A circuit uses a digitally controlled multistage cascade combiner, a digital phase and drive signal amplifier controller and a digital combiner controller circuit with N parallel signals with constant amplitudes belonging to an alphabet with M discrete values and discrete phases feeding it. The signals resulting from N power amplifiers (PAs) have also constant amplitudes belonging to an alphabet with N discrete values and discrete phases prior to being fed to the multistage combiner. A digital combiner controller circuit generates digital control information to activate, or deactivate, the outputs of the PAs, where a set of digital control signals generated in digital combiner controller are used to control sets of switches, where the signals can be activated at the combiner's inputs, according to their power and phase values. The digital control information ensures that only in-phase signals are combined in the active combiner stage and any difference among the inputs of the combiners is always minimized. Both digital combiner controller and digital drive signal amplifier controller, share information about the signals not to be fed to the multistage combiner, so that PAs drive signals can also be powered off under these circumstances. In provide high efficiency amplification the signal amplifiers employed before the combining stage may be of switched or current source type.