Balun Transformer Harmonic Filter Crossover Configuration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional transformers face a trade-off between efficiency and harmonic levels in power amplifiers, as ETSI standards require harmonic filtering which results in filter losses, affecting overall amplifier performance.
Innovation Solution
A crossover configuration is implemented in the secondary coil of the transformer, where a portion of the secondary inductor is shared between two resonators, and additional capacitors are used in parallel with the inductor to create harmonic traps, efficiently utilizing the secondary coil as a resonating element while maintaining ETSI harmonic levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional transformers are used with separate harmonic filtering components, then harmonic levels meet ETSI standards, but filter losses reduce overall amplifier efficiency
Solution Approach 1:
The patent combines the harmonic filter functionality with the transformer structure by integrating capacitive elements directly into the transformer circuit. The secondary winding is connected in parallel with a capacitor to ground, creating a resonant circuit that provides harmonic filtering while maintaining the transformer's impedance transformation function. This integration eliminates separate filter components and their associated losses.
Solution Approach 2:
The transformer structure is designed to perform multiple functions simultaneously: impedance transformation from balanced to unbalanced configuration, and harmonic filtering. The capacitive elements connected to the secondary winding serve dual purposes by establishing resonant frequencies that trap harmonics while the transformer maintains its primary signal transformation function.
2Object-affected harmful factors
If additional filtering components are added to meet ETSI standards, then harmonic rejection improves, but device complexity and area increase
Solution Approach 1:
The filtering function is merged into the existing transformer structure rather than adding separate filter components. The capacitor connected in parallel with the secondary winding creates a resonant circuit that provides harmonic rejection without requiring additional inductors or complex filter topologies.
Solution Approach 2:
The transformer structure is enhanced to provide both impedance transformation and harmonic filtering functions. The capacitive elements integrated into the transformer circuit enable multi-functionality, achieving harmonic rejection while maintaining the original transformer's primary function without significant complexity increase.
3Object-affected harmful factors
If traditional separate filter components are used, then harmonic levels are controlled, but cost and area are significantly impacted
Solution Approach 1:
The patent merges the harmonic filtering function with the transformer structure by integrating capacitive elements directly into the transformer circuit. This integration eliminates the need for separate filter components and their associated PCB space, achieving harmonic control within the existing transformer footprint.
Solution Approach 2:
The transformer structure is designed to perform multiple functions simultaneously: impedance transformation and harmonic filtering. The capacitive elements connected to the secondary winding provide harmonic rejection while occupying minimal additional area, as they share the transformer's physical space and component footprint.
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
This configuration enhances power amplifier efficiency with minimal impact on cost and area, achieving significant harmonic rejection with minimal reduction in maximum available gain.
Implementation Method 1
secondary inductor 22 is magnetically coupled with primary inductor 20
Implementation Method 2
Both primary and secondary coils (primary inductor 20 and secondary inductor 22) are resonated with capacitors (primary capacitor 18 and secondary capacitor 26 respectively) to present real impedances at the frequency of interest
Implementation Method 3
the harmonic levels at the unbalanced output port 24 must later be filtered (not shown) to meet the ETSI (European Telecommunications Standards Institute) standards at the antenna
Data Source
AI summary
In one embodiment, a balanced to unbalanced transformer utilizes a crossover configuration such that some portion of the secondary coil (inductor) is shared between two resonators (capacitors). Adding a first capacitor in parallel with a portion of the secondary inductor creates a first harmonic trap (filter), and also efficiently uses the secondary coil (inductor) as a resonating element.Adding a second capacitor which shares (crossover configuration) a portion of the secondary inductor with the first capacitor creates a second harmonic trap (filter), which may be tuned to the same harmonic as the first harmonic trap, or may be tuned to a different harmonic.