Envelope-Tracked Distributed Amplifier for Wideband PA Efficiency
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Solution Overview
Problem
Current power amplifiers in wireless networks face challenges in achieving high efficiency and wide bandwidth operation, particularly in supporting concurrent multi-band operations and LTE carrier aggregation, due to the limitations of resonant matching networks which result in narrow bandwidth efficiency and increased power consumption.
Innovation Solution
The integration of a distributed amplifier with an envelope tracking path provides an envelope tracked drain voltage to all transistors, combined with polar transmitter architectures, to enhance efficiency and bandwidth, using techniques such as envelope tracking and non-uniform distributed amplifier architectures, either in complete analog or combined digital-analog implementations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonant matching networks are used to match power amplifier to 50 ohm load, then power amplifier efficiency is improved, but bandwidth becomes narrow
Solution Approach 1:
The power amplifier is divided into multiple parallel amplifier sections, each with its own transistor and resonant matching network. This segmentation allows each section to operate at peak efficiency at its tuned frequency while the aggregate system provides wide bandwidth operation through the combination of multiple sections.
Solution Approach 2:
The distributed amplifier architecture serves multiple functions simultaneously: it provides wide bandwidth operation, maintains high efficiency across multiple bands, and supports concurrent multi-band operation. The parallel configuration of amplifier sections with different tuned frequencies enables the system to function efficiently across a broad frequency range.
2Adaptability or versatility
If multiple power amplifiers are employed for multi-band operation, then bandwidth coverage is improved, but device complexity increases
Solution Approach 1:
Multiple amplifier sections are merged into a single distributed amplifier structure where the parallel-connected transistors and their matching networks work together as one integrated system. This merging provides multi-band capability while reducing complexity compared to using completely separate power amplifier modules for each band.
Solution Approach 2:
The distributed amplifier structure provides universal multi-band operation capability through its parallel configuration of amplifier sections tuned to different frequencies. This single structure can operate across multiple bands simultaneously, eliminating the need for separate amplifier modules for each band.
3Device complexity
If conventional power amplifier architecture is used, then circuit simplicity is maintained, but power consumption increases in multi-band operations
Solution Approach 1:
The power amplifier is segmented into multiple parallel sections, each optimized for specific frequency bands. This allows the amplifier to operate efficiently across wide bandwidth by distributing the amplification task across sections, reducing overall power consumption compared to a single conventional amplifier operating across all bands.
Solution Approach 2:
The amplifier sections are designed with different tuned frequencies and impedance parameters optimized for specific bands. By changing the operating parameters (tuned frequency, impedance) of individual sections, the system achieves wide bandwidth operation with reduced power consumption compared to a conventional single-parameter amplifier.
Data Source
Figure 1~2a
Figure 2b
Figure 3
AI summary
A system and method amplify a waveform in a wireless network. An envelope of a waveform is detected to form an envelope waveform. The envelope waveform is shaped to form a shaped waveform, the shaping based on one or more characteristics of a distributed amplifier. The shaped waveform is filtered to form a filtered waveform. The filtered waveform is amplified to form a first amplified waveform. The distributed amplifier amplifies at least a part the waveform based on the first amplified waveform to form a second amplified waveform.