Balanced LINC Output Network Using Balun Conversion
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Solution Overview
Problem
Balanced class B, E/F, and current mode class D (CMCD) power amplifiers present a challenge when combined with LINC networks due to their balanced output and the need for high power, low loss transformers that are difficult to realize at cellular frequencies.
Innovation Solution
A balanced power amplifier network is integrated with a LINC or Chireix outphasing technique, utilizing a balanced lossless output combination network and balun arrangements to convert between balanced and unbalanced operations, allowing for high linearity and wide bandwidth while maintaining efficiency across different peak-to-average power ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If balanced class B, E/F, or CMCD power amplifiers are used to achieve high efficiency, then efficiency is improved, but the compatibility with LINC networks deteriorates due to balanced output requirements
Solution Approach 1:
A balun arrangement serves as an intermediary device between the balanced power amplifier and the single-ended LINC network. The balun converts the balanced output signals from the amplifier into unbalanced signals suitable for the LINC network, enabling compatibility without sacrificing the efficiency benefits of balanced amplifiers.
Solution Approach 2:
The invention introduces asymmetry by using a balun arrangement that converts symmetric balanced signals into asymmetric unbalanced signals. This allows the balanced amplifier to interface with the single-ended LINC network, resolving the compatibility issue while maintaining amplifier efficiency.
2Reliability
If high power low loss transformers are used to interface balanced amplifiers with LINC networks, then signal transmission is improved, but device complexity and manufacturing difficulty increase at cellular frequencies
Solution Approach 1:
The balun arrangement acts as an intermediary that avoids the need for complex high power low loss transformers at cellular frequencies. It provides the necessary signal conversion while being more practical and manufacturable for modern radio frequency applications.
Solution Approach 2:
The invention replaces the mechanical/physical transformer system with an electromagnetic balun arrangement that achieves the same signal conversion function with reduced complexity and improved manufacturability at cellular frequencies.
3Ease of manufacture
If unbalanced class A, B, or C amplifiers are used with LINC networks, then ease of manufacture is improved, but efficiency deteriorates compared to balanced amplifiers
Solution Approach 1:
The invention introduces asymmetry through the balun arrangement, allowing symmetric balanced amplifiers to interface with asymmetric single-ended LINC networks. This enables the use of efficient balanced amplifiers instead of less efficient unbalanced amplifiers, while still maintaining ease of manufacture through standard balun designs.
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.