Balanced Output Network for LINC Outphasing Amplifiers
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Solution Overview
Problem
Current technologies face challenges in combining balanced power amplifiers like class B, E/F, and current mode class D (CMCD) amplifiers with LINC or Chireix outphasing networks due to the mismatch between the balanced output of these amplifiers and the single-ended nature of LINC networks, requiring a high power, low loss transformer that is difficult to realize at cellular frequencies.
Innovation Solution
A composite power amplifying system that incorporates balanced power amplifiers with a LINC or Chireix outphasing technique, utilizing a balanced lossless output combination network and a balun arrangement to convert balanced to unbalanced operation, allowing for high linearity and wide bandwidth while maintaining efficiency across different peak-to-average power ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If balanced power amplifiers (class B, E/F, CMCD) are combined with LINC or Chireix outphasing networks, then high efficiency and wide bandwidth are achieved, but the mismatch between balanced amplifier output and single-ended LINC network requires a high power low loss transformer that is difficult to realize at cellular frequencies
Solution Approach 1:
The patent introduces a balun arrangement as an intermediary component that converts the balanced output from the power amplifiers into a single-ended signal suitable for the LINC or Chireix outphasing network. This balun arrangement acts as a mediator that resolves the impedance and configuration mismatch between the balanced amplifiers and the single-ended network, eliminating the need for complex high power transformers while maintaining signal integrity and efficiency.
Solution Approach 2:
The patent replaces the mechanical/physical transformer solution with an electrical balun arrangement that performs the same function through electromagnetic coupling and impedance transformation. This substitution eliminates the physical constraints and losses associated with traditional transformers at cellular frequencies, providing a more practical and efficient solution for combining balanced amplifiers with outphasing networks.
2Ease of manufacture
If unbalanced amplifiers (class A, B, C, E, F) are used with LINC or Chireix networks, then the system is easier to implement, but the efficiency region is limited and does not include lower output power levels
Solution Approach 1:
The patent employs asymmetric configuration in the balun arrangement and output combination network to extend the efficiency region. By carefully designing the impedance transformation ratios and network topology, the system maintains high efficiency across a wider range of output power levels, including lower power levels where traditional unbalanced amplifier configurations fail to maintain efficiency.
Solution Approach 2:
The patent implements dynamic impedance matching through the balun arrangement and output combination network, allowing the system to adapt its impedance characteristics across different output power levels. This dynamic adaptation enables the amplifier to maintain high efficiency whether operating at peak power or lower power levels, significantly extending the useful efficiency region compared to static unbalanced configurations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high linearity and wide bandwidth by enabling the use of balanced amplifiers with LINC or Chireix outphasing methods, preserving the ability to adjust efficiency curves and supporting efficient power amplification in radio transmitters, particularly in cellular systems.
Implementation Method 1
a balun arrangement to convert balanced to unbalanced operation
Data Source
AI summary
The present invention relates to balanced power amplifier network in combination with outphasing techniques such as Chireix. The object of the present invention is to provide a solution to the problem to combine balanced amplifiers like the current mode class D (CMCD) or class E/F with a LINC network. The main problem is that some power amplifiers have balanced output and the LINC network is single-ended so that a high power low loss transformer that works at several impedance levels is needed, which is hard to realize at cellular frequencies.