Differential Transmission Line Filtering for Wireless Noise Suppression
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Solution Overview
Problem
Existing electronic apparatuses struggle to effectively reduce radiation noise, particularly self-poisoning electromagnetic noise, which adversely affects other functions and external devices.
Innovation Solution
A wireless circuit-mounted electronic apparatus is designed with an absorption-type filter mounted on transmission lines, which absorbs noise and prevents its leakage, combined with specific configurations such as choke coils and capacitors to manage noise frequencies and reduce radiation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a common mode choke coil is used to block common mode noise, then radiation noise is reduced, but self-poisoning electromagnetic noise is not effectively suppressed
Solution Approach 1:
The noise filtering function is segmented into two distinct components: a common mode choke coil for blocking common mode noise and an absorption-type filter for absorbing self-poisoning electromagnetic noise. This segmentation allows each component to specialize in handling specific noise types, resolving the contradiction by addressing both radiation noise and self-poisoning noise with dedicated solutions.
Solution Approach 2:
The absorption-type filter acts as an intermediary component between the common mode choke coil and the transmission line. It absorbs the self-poisoning electromagnetic noise that the choke coil cannot block, converting it into heat energy. This intermediary approach allows the system to handle multiple noise types effectively without interference between the different noise suppression mechanisms.
2Object-affected harmful factors
If a reflection-type filter is used to reduce radiation noise, then electromagnetic radiation is suppressed, but standing waves are generated in transmission lines
Solution Approach 1:
Instead of reflecting the self-poisoning electromagnetic noise (which would create standing waves), the absorption-type filter converts the harmful noise energy into heat energy through resistance. This transformation of harm into a harmless form (heat) effectively suppresses both radiation noise and standing wave generation, resolving the contradiction by eliminating the root cause rather than merely reflecting it.
Solution Approach 2:
The absorption-type filter changes the impedance parameter along the transmission line by introducing a resistive component. This impedance transformation allows the filter to absorb noise energy rather than reflect it, thereby suppressing radiation noise without creating standing waves. The parameter change from pure reactance (in reflection filters) to resistance (in absorption filters) resolves the contradiction.
3Object-generated harmful factors
If existing filter circuits are used without specific mounting position optimization, then noise absorption is achieved, but effective usage method is not realized
Solution Approach 1:
The patent specifies the optimal mounting position of the absorption-type filter in advance (at a distance of about 1/4 wavelength or more from the noise generation source). This preliminary determination of the correct position eliminates the need for trial-and-error installation and ensures effective noise absorption from the outset, resolving the contradiction between achieving noise absorption and ease of effective implementation.
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 effectively suppresses electromagnetic radiation noise and self-poisoning, ensuring minimal interference with external devices and maintaining apparatus functionality.
Implementation Method 1
an absorption-type filter that is mounted on the transmission lines and absorbs noise mixed in the transmission lines
Implementation Method 2
the resistor absorbs energy of the common mode noise into heat for consumption
Implementation Method 3
The first choke coil transmits a normal mode signal and blocks common mode noise
Implementation Method 4
an antenna that has a gain in a frequency band of the noise which is generated in the noise generation source; and a wireless signal processing circuit that processes a signal received by the antenna
Data Source
AI summary
A signal transmission and reception element transmits and receives a differential signal. Two transmission lines transmit the differential signal between the signal transmission and reception element and a connector. The signal transmission and reception element is connected to an external apparatus with the connector interposed therebetween. A noise generation source generates noise in a wireless band, which is coupled to the transmission lines. An antenna has a gain in a frequency band of the noise which is generated in the noise generation source. A wireless signal processing circuit processes a signal received by the antenna. An absorption-type filter that is mounted on the transmission lines absorbs noise mixed in the transmission lines.