Balanced Amplifier Load Modulation for Wideband Power Back-Off
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Solution Overview
Problem
Conventional load-modulation techniques face challenges in efficiently transmitting high-PAPR signals and extending to wider bandwidths, while maintaining maximized efficiency over extended power back-off and frequency spans.
Innovation Solution
The proposed pseudo-Doherty load-modulated balanced amplifier (PD-LMBA) architecture combines a carrier amplifier and a balanced amplifier with proper phase and amplitude controls, allowing for optimal load-modulation behavior and achieving maximized efficiency over extended power back-off ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional load-modulation techniques (e.g., standard DPA) are used, then efficiency can be improved at peak power, but bandwidth is strongly limited by quarter-wave inverter
Solution Approach 1:
The amplifier is divided into two independent balanced amplifier paths, each with its own quarter-wave inverters operating at different frequency ranges. This segmentation allows each path to be optimized for specific bandwidth regions while maintaining overall wideband operation, resolving the contradiction between efficiency and bandwidth by distributing the operational burden across multiple specialized segments.
Solution Approach 2:
The invention transitions from a single-frequency optimization approach to a multi-frequency dimension approach by employing two balanced amplifier paths tuned to different center frequencies. This dimensional expansion in frequency space allows the system to achieve wideband operation while maintaining high efficiency at each frequency point, effectively breaking the conventional efficiency-bandwidth tradeoff.
2Loss of energy
If supply modulation (envelope tracking) is used to enhance PA efficiency, then efficiency can be improved, but bandwidth limitation and system complexity increase
Solution Approach 1:
The invention extracts and eliminates the envelope tracking supply modulation mechanism from the system, replacing it with a load-modulation approach using balanced amplifier paths. By removing the complex supply modulation circuitry while achieving the same efficiency enhancement through a different mechanism, the system reduces bandwidth limitations and operational complexity while maintaining improved power amplifier efficiency.
Solution Approach 2:
The invention introduces balanced amplifier paths with quarter-wave inverters as intermediary components that perform load modulation. These intermediaries achieve efficiency enhancement through impedance transformation and load modulation rather than through complex supply modulation, thereby simplifying the overall system operation while maintaining high efficiency.
3Adaptability or versatility
If standard DPA architecture is used, then 6 dB back-off power range is achieved, but efficiency over extended power back-off and broadened frequency span cannot be maintained
Solution Approach 1:
The invention employs dynamically adjustable balanced amplifier paths that can be independently controlled and optimized for different operating conditions. Each balanced amplifier path can be dynamically tuned to provide optimal performance across different power back-off levels and frequency ranges, allowing the system to maintain high efficiency over extended power back-off (10 dB) and broadened frequency spans simultaneously.
Data Source
AI summary
Described herein are load-modulated balanced amplifiers. An example load-modulated balanced amplifier can include a radio frequency (RF) input port, a RF output port, a peaking amplifier circuit operably coupled between the RF input and RF output ports, where the peaking amplifier circuit is a balanced amplifier that includes a pair of power amplifiers, and a carrier amplifier circuit operably coupled to the RF input port.