Active Twisted Figure 8 Inductor Parasitic Coupling
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Solution Overview
Problem
Conventional figure '8' inductor topologies exhibit reduced electrical performance and are less attractive for high-end VCO applications due to significant parasitic magnetic coupling, which affects the phase noise performance and immunity to parasitic coupling.
Innovation Solution
An active twisted figure '8' inductor design featuring a plurality of lobes with generators and interconnects that arrange magnetic fields of opposite polarity, allowing for better phase noise performance and immunity to parasitic coupling by actively driving lobes with cross-coupled interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a figure '8' shaped inductor topology is used to minimize magnetic sensitivity, then parasitic magnetic coupling is reduced (40 to -70 dB), but electrical performance significantly deteriorates
Solution Approach 1:
The inductor is divided into multiple lobes (typically two or four) arranged in a figure-8 configuration, with each lobe independently driven by separate current sources. This segmentation allows independent control of magnetic field polarity in each lobe, enabling cancellation of parasitic magnetic coupling while maintaining electrical performance through active balancing of the segmented sections.
Solution Approach 2:
The invention dynamically adjusts the current magnitude and polarity parameters in each lobe to optimize performance. By changing the electrical parameters (current direction, amplitude) of each segmented lobe based on operating conditions, the system maintains low parasitic coupling across different frequency and power levels while preserving electrical performance.
2Ease of manufacture
If conventional passive figure '8' inductor topology is used, then manufacturing is simpler, but phase noise performance degrades by 3-6 dBc compared to active designs
Solution Approach 1:
The invention transitions from a static passive inductor to a dynamic active structure where multiple current sources continuously adjust their output to maintain optimal magnetic field cancellation. This dynamic operation reduces phase noise by 3-6 dBc compared to passive designs while keeping the physical footprint and manufacturing process similar to conventional inductors.
Solution Approach 2:
The active figure-8 inductor employs feedback mechanisms where the output magnetic field is monitored and used to adjust the current in each lobe. This feedback control enables real-time optimization of the magnetic cancellation effect, significantly improving phase noise performance while maintaining manufacturing simplicity through standard integrated circuit processes.
3Object-affected harmful factors
If multiple lobes with independent generators are used to arrange magnetic field polarity, then immunity to parasitic coupling improves, but device complexity increases
Solution Approach 1:
The invention combines multiple current sources and lobe structures into a unified figure-8 configuration where the lobes are magnetically coupled through shared magnetic paths. This merging approach achieves high immunity to parasitic coupling by coordinating the magnetic fields of combined lobes, while the integrated design prevents excessive complexity increase.
Solution Approach 2:
The interconnects serving lobes act as intermediaries that coordinate current distribution between multiple generators. These interconnect structures enable the complex multi-lobe configuration to achieve high parasitic coupling immunity while managing device complexity through standardized connection patterns and balanced current distribution networks.
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 active twisted figure '8' inductor achieves improved phase noise performance and maintains immunity to parasitic coupling, outperforming conventional passive inductors by approximately 3-6 dBc, while allowing for various configurations without electrical parameter degradation.
Implementation Method 1
each of the generators coupled to a corresponding one of the plurality of lobes... magnetic fields generated in each of the lobes has an arranged polarity relative to the other lobes
Data Source
AI summary
An inductor is disclosed that includes an arrangement of lobes, each of the lobes in the arrangement of lobes including a generator, the arrangement of lobes interconnected such that, when currents are provided by each generator in the arrangement of lobes, each lobe in the arrangement of lobes produces a magnetic field with a defined polarity relative to the arrangement of lobes. When the arrangement of lobes are appropriately interconnected, the magnetic field from the arrangement of lobes can be canceled.