Passive Polyphase Filter for TV Nyquist Slope Integration
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Solution Overview
Problem
Existing filter devices for receiving television signals struggle to integrate a Nyquist slope effectively for both analog and digital signals, requiring multiple SAW filters for different standards and lacking a common solution for hybrid reception.
Innovation Solution
A filter device utilizing a passive polyphase filter with multiple simple stages, where each stage connects input phases through resistors and capacitors to form a Nyquist slope, allowing for use with window-SAW filters and achieving linearity without active components, and can be extended to suppress image frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple external SAW filters are used for different television standards, then the Nyquist slope can be formed for each standard, but the device complexity and integration expenditure increase significantly
Solution Approach 1:
The patent implements a universal filter device that can form Nyquist slopes for multiple television standards (PAL, NTSC, SECAM) using a single polyphase filter structure. The filter achieves multi-functionality by configuring passive components (resistors and capacitors) to create different filter characteristics through component selection and arrangement, eliminating the need for multiple separate SAW filters while maintaining compatibility with various TV standards
Solution Approach 2:
The patent combines the functions of multiple separate SAW filters into a single integrated polyphase filter device. By merging the filtering functions for different television standards into one device with configurable passive components, the solution reduces the overall number of filters needed while maintaining the ability to form appropriate Nyquist slopes for each standard through proper component configuration
2Adaptability or versatility
If a window-SAW-filter is used for digital television signals, then digital reception is achieved, but the integration of Nyquist slope for analog television signal reception becomes complex
Solution Approach 1:
The patent designs a universal polyphase filter that serves dual purposes: forming Nyquist slopes for analog television signals and providing channel selectivity for digital television signals. The same filter structure can be configured through passive component selection to accommodate both analog and digital reception requirements, eliminating the need for separate filter solutions for each signal type
3Reliability
If external SAW filters are used, then channel selectivity and Nyquist slope are achieved, but the device requires more integration resources and space
Solution Approach 1:
The patent replaces the mechanical/crystalline SAW filter structure with an electrical polyphase filter implementation using passive RC components. This substitution achieves the same channel selectivity and Nyquist slope formation functions through electrical circuitry rather than acoustic wave mechanisms, reducing integration complexity and expenditure while maintaining the required filtering performance
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 enables reduced integration expenditure and a common filter for both analog and digital signals, achieving amplitude alignment between double-sideband and single-sideband ranges, while maintaining linearity and reducing interference from adjacent channels.
Implementation Method 1
the filter device forms a Nyquist slope by means of a passive polyphase filter
Implementation Method 2
A RC polyphase filter outputs a corresponding polyphase phase-shifted current signal Co according to supplying of the input current signal Ci
Implementation Method 3
a window-SAW-filter is used instead of a multiplicity of SAW filters
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The invention relates to a filter device particularly for receiving television signals, which receives input signals and generates output signals, wherein the filter device forms a Nyquist slope by means of a passive polyphase filter (10).