On-Chip Balun Transformer With Nested Semi-Turn Coils
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Solution Overview
Problem
On-chip balun transformers face challenges in achieving high impedance matching and low impedance matching while maintaining a high coupling factor, especially as wireless communication devices operate at increasingly higher frequencies, leading to voltage conversion losses.
Innovation Solution
The design incorporates a primary winding with both parallel and serial semi-turn coils and a secondary winding with serial semi-turn coils, both being coplanar and magnetically coupled, forming a 7-layered structure on a semiconductor substrate to enhance coupling and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the on-chip balun transformer uses a conventional winding structure, then the manufacturing process is simple, but the coupling factor is low and voltage conversion loss is high
Solution Approach 1:
The primary winding is divided into multiple parallel coil groups, each group containing multiple parallel coils. The secondary winding is divided into multiple serial semi-turn coils. This segmentation increases the coupling factor and reduces voltage conversion loss by creating more coupling paths between windings.
Solution Approach 2:
The secondary winding coils are positioned within the area occupied by the primary winding coils, creating a nested configuration. This nested structure maximizes magnetic coupling between the windings while maintaining a compact on-chip footprint, thereby reducing voltage conversion loss.
2Reliability
If the on-chip balun transformer uses a symmetrical winding structure, then the manufacturing precision is easier to control, but the impedance matching performance is limited
Solution Approach 1:
The primary winding uses an asymmetrical configuration with parallel coil groups having different numbers of turns and different areas. This asymmetry enables flexible impedance transformation ratios and improves impedance matching performance between different impedance levels while maintaining reliable operation.
3Speed
If the on-chip balun transformer is designed for high frequency operation, then the communication capability is improved, but the voltage conversion loss increases due to parasitic effects
Solution Approach 1:
The transformer uses a planar coplanar configuration where both primary and secondary windings lie on the same chip plane. This dimensional arrangement reduces parasitic inductance and capacitance compared to traditional three-dimensional structures, enabling high-frequency operation with reduced voltage conversion loss.
4Area of stationary object
If the on-chip balun transformer uses a coplanar structure, then the integration density is improved, but the magnetic coupling between windings is reduced
Solution Approach 1:
The secondary winding coils are nested within the primary winding area, maximizing the use of available chip space. This nested coplanar configuration maintains strong magnetic coupling between windings while achieving high integration density and efficient chip area utilization.
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 reduces resistance values and increases the coupling factor, enabling effective impedance matching and minimizing voltage conversion losses, suitable for high-frequency applications.
Implementation Method 1
The secondary winding, being a symmetrical winding inductor and magnetically coupled to the primary winding
Data Source
AI summary
An on-chip balun transformer including a primary winding and a secondary winding is provided. The primary winding includes at least one parallel coil and a plurality of first serial semi-turn coils connected to the at least one parallel coil. The secondary winding, magnetically coupled to the primary winding, includes a plurality of second serial semi-turn coils connected to each other. At least one of the second serial semi-turn coils is located within the at least one parallel coil. The primary winding and the secondary winding are coplanar.