Planar Inductor TV Band-Pass Filter for Easier PCB Tuning
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Solution Overview
Problem
The existing band-pass filters in TV signal distribution devices require complex and costly fabrication processes due to the use of aerial coils, which demand skilled labor and expensive machinery for tuning and shaping, limiting production capacity and increasing costs.
Innovation Solution
The use of planar inductors embedded in a dielectric environment replaces aerial coils, allowing for faster, more economical production and integration with other components, reducing the need for manual tuning and shielding, and enabling improved selectivity through cascaded filter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aerial coils are used in band-pass filter circuits, then high quality factor and good selectivity are achieved, but fabrication complexity and cost increase significantly
Solution Approach 1:
The patent replaces mechanical aerial coils with planar inductors fabricated on PCB substrates using standard PCB manufacturing processes. This substitution eliminates the need for manual coil shaping and mechanical assembly, while maintaining the electrical functionality through planar spiral or meander patterns that provide the required inductance values.
Solution Approach 2:
The patent changes the physical form and fabrication parameters of the inductors from three-dimensional aerial coils to two-dimensional planar structures. This parameter change allows the inductors to be manufactured using standard PCB processes with controlled impedance, eliminating manual tuning while maintaining electrical performance through optimized trace geometry and substrate selection.
2Manufacturing precision
If aerial coils are manually shaped and tuned, then target frequency characteristics are achieved, but production time and labor costs increase
Solution Approach 1:
The patent performs the tuning action preliminarily during the PCB design and fabrication stage rather than during final assembly. The planar inductor geometry, trace width, trace length, and substrate properties are pre-calculated and built-in to achieve the exact target inductance value, eliminating the need for post-fabrication manual tuning and enabling high-volume production.
Solution Approach 2:
The patent makes the filter circuit self-tuning through precise PCB fabrication tolerances and controlled impedance design. The planar inductors are designed with built-in compensation for manufacturing variations, and the overall filter response is optimized through simulation and iterative design, allowing the circuit to achieve target characteristics without manual intervention.
3Reliability
If expensive machinery and skilled labor are used for coil fabrication, then high quality factor is achieved, but product cost increases
Solution Approach 1:
The patent extracts the inductor function from specialized aerial coil components and integrates it directly into the PCB structure. This extraction eliminates the need for separate coil components, specialized fabrication equipment, and skilled manual assembly, while maintaining the required quality factor through optimized PCB layer design, copper weight selection, and substrate material choice.
Solution Approach 2:
The patent makes the PCB substrate serve multiple functions: it provides mechanical support, electrical connectivity, impedance control, and inductance generation through its planar trace patterns. This multi-functionality consolidates multiple components and processes into a single standardized manufacturing platform, reducing overall system cost while maintaining performance.
4Manufacturing precision
If manual tuning processes are implemented, then filter characteristics are optimized, but production time and complexity increase
Solution Approach 1:
The patent replaces manual mechanical tuning processes with automated PCB fabrication processes. The planar inductor parameters are precisely controlled through CAM software and automated routing, ensuring consistent electrical characteristics across all units without manual intervention, thereby eliminating production time loss while maintaining optimization precision.
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 solution reduces production costs and complexity, enhances reproducibility, and improves selectivity by minimizing parasitic feedback and signal leakage, while allowing for easier integration and control of filter parameters using Surface Mount Technology (SMT) and PCB substrates.
Implementation Method 1
The planar inductors are mechanically fixed and embedded in a dielectric environment
Implementation Method 2
The most suitable components for retuning are varicap diodes which can be used as a voltage-controlled capacitor if they are operated reverse-biased
Data Source
Figure 1~3
Figure 4~5
Figure 6
AI summary
TV signal distribution filter device comprising at least one tuneable band- pass filter circuit, each tuneable filter circuit having a signal input (1) for receiving a TV signal, a signal output (17) for delivering a filtered TV signal, and a plurality of components connected in a predetermined configuration between the signal input and the signal output and together being provided for filtering the received TV signal to the filtered TV signal, said plurality of components comprising at least a first inductor (8) and a second inductor (10), each accompanied by a tuneable capacitive component (5, 11) and connected to a voltage node (2, 18) which is provided for receiving a tuning voltage for tuning the tuneable capacitive component and thereby setting a filtering parameter of the tuneable filter circuit, the first and second inductors being planar inductors which are mechanically fixed and embedded in a dielectric environment (19; 20; 21) and are electro-magnetically coupled with each other.