Liquid Crystal Tunable Band-Stop Filter
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Solution Overview
Problem
Current tunable band-stop filters face limitations such as low operation frequency, complex processes, high costs, large losses, and strong nonlinear noise, which restrict their application scenarios, and liquid crystal materials exhibit limited tuning rates in the microwave band.
Innovation Solution
A tunable band-stop filter is designed using a liquid crystal layer sandwiched between substrates with wire structures and a common electrode, employing phase reverse cancellation and a variable dielectric constant to control the filtering frequency range, featuring a simple structure, wide operation frequency range, low loss, and large regulation range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If diode-based or MEMS-based tunable band-stop filters are used, then the filtering function is achieved, but the operation frequency is limited and the device complexity increases
Solution Approach 1:
The patent replaces mechanical or electronic tuning mechanisms (diodes, MEMS) with a liquid crystal-based electromagnetic field control system. The liquid crystal layer's variable dielectric constant under electromagnetic field control enables frequency tuning without mechanical moving parts or complex electronic circuits, thus increasing operation frequency while reducing device complexity
Solution Approach 2:
The patent changes the dielectric constant parameter of the liquid crystal material through external control to achieve frequency tuning. By varying the dielectric constant of the liquid crystal layer between substrates, the filtering frequency can be adjusted dynamically, enabling wide operation frequency range without complex structural changes
2Reliability
If ferrite or ferroelectric materials are used for tuning, then the filtering performance is improved, but the loss increases and nonlinear noise becomes strong
Solution Approach 1:
The patent uses a composite structure combining liquid crystal materials with substrate and electrode layers. The liquid crystal layer, positioned between the first and second substrates, provides tunable dielectric properties without the high loss and nonlinear characteristics of ferrite or ferroelectric materials, achieving reliable filtering performance with low energy loss
Solution Approach 2:
The patent employs liquid crystal material which exhibits lower loss and better linearity compared to ferrite or ferroelectric materials. Although liquid crystals require external control, their inherent low loss characteristics and reduced nonlinear noise make them a more efficient choice for maintaining filtering performance
3Device complexity
If liquid crystal materials are used, then the structure becomes simpler and cost reduces, but the tuning rate is limited in microwave band
Solution Approach 1:
The patent enhances the static liquid crystal material's tuning capability by introducing dynamic control through external electromagnetic fields. The liquid crystal layer's dielectric constant can be dynamically adjusted, enabling wide frequency tuning range in the microwave band while maintaining simple structure and low cost
Solution Approach 2:
The patent makes the liquid crystal-based filter multi-functional by enabling it to operate across a wide frequency range through external control. The same simple structure can be tuned to different frequencies, providing adaptability and versatility without requiring multiple specialized components
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 solution provides an efficient tunable band-stop filter with a wide effective operation frequency range, low production cost, small loss, and large regulation range, effectively attenuating electromagnetic waves in specific frequency ranges using phase reverse cancellation and dielectric constant control.
Implementation Method 1
liquid crystal materials exhibit limited tuning rates in the microwave band
Implementation Method 2
the first wire structure, the common electrode and a liquid crystal layer between the first wire structure and the common electrode constitute a first phase modulation structure
Implementation Method 3
a first endpoint of the first wire structure is connected to a first endpoint of the second wire structure, a second endpoint of the first wire structure is connected to a second endpoint of the second wire structure
Implementation Method 4
employing phase reverse cancellation and a variable dielectric constant to control the filtering frequency range
Data Source
AI summary
A tunable band-stop filter, a method of driving a tunable band-stop filter and an electronic device are provided. The tunable band-stop filter includes a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate. The first substrate includes a wire structure on a first base substrate, the second substrate includes a common electrode on a second base substrate. The wire structure includes a first wire structure and a second wire structure. The first wire structure, the common electrode, and the liquid crystal layer between the first wire structure and the common electrode constitute a first phase modulation structure, and the second wire structure, the common electrode, and the liquid crystal layer between the second wire structure and the common electrode constitute a second phase modulation structure.