Distributed Power Amplifier Supply Segmentation for Wideband Efficiency
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Solution Overview
Problem
Conventional power amplifiers face inefficiencies at low signal amplitudes and have limitations in bandwidth and output power, particularly in wideband applications, where achieving high average efficiency is compromised by sacrificing maximum power efficiency and increasing transistor costs.
Innovation Solution
A distributed power amplifier design with multiple sets of sub-amplifiers along the output transmission line, utilizing different supply voltages and characteristic impedances to optimize efficiency and minimize ripples across a wide range of input signal amplitudes and frequencies, allowing for high efficiency over a large relative bandwidth with reduced output signal ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power amplifiers operate at backed off levels to handle low signal amplitudes, then average efficiency is improved, but maximum output power capability is reduced
Solution Approach 1:
The power amplifier is divided into multiple independent sub-amplifiers that can be selectively activated. Each sub-amplifier handles a portion of the total output power requirement, allowing the system to operate efficiently at low power levels by activating only necessary sub-amplifiers while maintaining the capability to deliver full power when all sub-amplifiers are active.
Solution Approach 2:
The amplifier dynamically adjusts the number of active sub-amplifiers based on the instantaneous signal amplitude. This dynamic reconfiguration allows the system to optimize efficiency for low signal levels by using fewer sub-amplifiers while maintaining full power capability when the signal amplitude increases, effectively resolving the trade-off between average efficiency and maximum output power.
2Loss of energy
If Doherty type amplifiers are used to improve efficiency for amplitude-modulated signals, then average efficiency is improved, but bandwidth is reduced due to reactive circuits
Solution Approach 1:
The invention changes the fundamental operating parameters from reactive circuit-based frequency-dependent operation to distributed sub-amplifier operation with frequency-independent characteristics. By using multiple sub-amplifiers with appropriate impedance matching networks, the system achieves wideband operation while maintaining high efficiency for amplitude-modulated signals, eliminating the narrowband limitation of traditional Doherty amplifiers.
3Adaptability or versatility
If wideband Doherty amplifiers are designed to increase bandwidth, then bandwidth is improved, but efficiency at maximum power and transistor utilization are reduced
Solution Approach 1:
The wideband requirement is satisfied by segmenting the amplifier into multiple sub-amplifiers that are distributed along the output transmission line. Each sub-amplifier operates independently and can be optimized for broad frequency response. The distributed configuration with proper impedance matching allows the system to maintain high efficiency at maximum power while achieving wideband operation, avoiding the efficiency losses associated with conventional wideband Doherty designs.
4Loss of energy
If multiple sub-amplifiers are distributed along the output transmission line, then efficiency and bandwidth are improved, but device complexity increases
Solution Approach 1:
Multiple supply voltages are merged into a single voltage rail by using DC-DC converters that generate the required different voltage levels from one input supply. This approach maintains the efficiency benefits of having different supply voltages for different sub-amplifiers while significantly reducing the complexity of the power supply network, as only one input supply and a few converters are needed instead of multiple independent supply sources.
Data Source
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AI summary
A power amplifier (100, 200, 500, 800, 1100) for amplifying an input signal into an output signal is disclosed. The power amplifier (100, 200, 500, 800, 1100) comprises an input port (110) for receiving the input signal and an output port (130) coupled to an output transmission line (140) for providing the output signal. The power amplifier (100, 200, 500, 800, 1100) further comprises multiple sets of sub-amplifiers (150, 160, 170, 180) distributed along the output transmission line, and inputs of the sub-amplifiers are coupled to the input port, outputs of the sub-amplifiers are coupled to the output transmission line. At least two different supply voltages are provided for the sub-amplifiers in the multiple sets of sub-amplifiers (150, 160, 170, 180).