Bridge Predistortion Linearizer With Dual Equalizers for Broadband PA Response
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Solution Overview
Problem
Current power amplifier linearizers have limited frequency response adjustment capabilities, particularly in the GHz range, due to parasitic effects from stray capacitances and bonding inductances, which restricts their ability to provide broadband linearization across the entire operating frequency band.
Innovation Solution
Incorporating equalizer stages in both the linear and non-linear bridge branches to insert precise amplitude and phase responses, allowing for compensation of parasitic effects and achieving desired broadband expansion, with the option of using passive or active elements like diodes and transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If equalizer stages are added to both bridge branches for precise frequency response adjustment, then broadband linearization capability is improved, but device complexity increases
Solution Approach 1:
The linearizer is divided into two independent bridge branches (linear and non-linear), each equipped with its own equalizer stage. This segmentation allows independent optimization of frequency response in each branch, enabling precise broadband linearization while maintaining modular structure that manages complexity.
Solution Approach 2:
Equalizer stages are selectively placed in specific locations within the bridge topology - specifically in both the linear and non-linear branches. This local placement targets the exact points where frequency response adjustment is most effective, providing precise control over the overall frequency response without unnecessarily complicating the entire system.
2Manufacturing precision
If equalizer stages with adjustable transfer functions are implemented, then compensation precision for parasitic effects is improved, but manufacturing complexity increases
Solution Approach 1:
The equalizer stages incorporate adjustable transfer functions that allow dynamic modification of amplitude and phase characteristics. This parameter adjustability enables precise compensation for parasitic effects and production lot variations without requiring complex manufacturing tolerances, as the compensation is achieved through programmable parameter adjustment rather than precise physical fabrication.
3Adaptability or versatility
If the linearizer is designed for broadband operation across the entire frequency band, then frequency coverage is improved, but control over frequency response becomes more difficult due to parasitic effects
Solution Approach 1:
Equalizer stages are introduced as intermediary components between the signal source and the power amplifier within the bridge structure. These equalizers act as mediators that actively compensate for parasitic effects by introducing opposite phase and amplitude corrections, thereby maintaining control over frequency response across the entire broadband frequency range despite the presence of parasitic elements.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a predistortion linearizer for a power amplifier using a bridge topology, having the advantages that an equalizer stage (4 and, respectively, 5) is arranged in the linear and non-linear bridge arm (7 and, respectively, 8). This equalizer stage serves to compensate for the frequency response of the complex expansion of the bridge. The equalizers insert adjustable transmission functions in the linear and non-linear bridge arms, and therefore the linearizer compensates for the individual non-linear frequency response of a power amplifier, said frequency response varying within a production batch.