RF Filter Paths With Adjacent Stopband and Low Passband Ripple
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Solution Overview
Problem
Existing RF filtering circuitry faces challenges in increasing out-of-band rejection without significantly increasing ripple variation in passbands, as traditional methods like LC notch filters load the filter paths and introduce excessive flyback, leading to power transfer inefficiencies and interference.
Innovation Solution
The RF filtering circuitry employs weakly coupled resonators and additional filter paths configured to create stopbands adjacent to passbands without substantial loading, using parallel and series resonators to define passbands and stopbands while minimizing ripple variation and flyback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LC notch filters are used to increase out of band rejection, then the roll-off of the passband is increased, but the ripple variation in the passbands is increased and excessive flyback is introduced
Solution Approach 1:
The patent introduces a second RF filter path as an intermediary element coupled to the first RF filter path. This second filter path creates a stopband adjacent to the passband without directly loading the first filter path, thereby achieving increased out of band rejection while minimizing ripple variation. The intermediary filter path acts as a mediator that provides the desired filtering effect without the harmful side effects of traditional notch filters.
2Reliability
If filtering components are added to create notches and increase roll-off, then out of band rejection is improved, but power transfer efficiency is reduced due to loading effects
Solution Approach 1:
The patent segments the filtering function into two separate RF filter paths. The first filter path handles the primary passband transmission with minimal loading, while the second filter path handles the stopband rejection function. This segmentation allows each path to be optimized for its specific function, preventing the loading effects that would otherwise reduce power transfer efficiency in a single integrated filter design.
3Reliability
If notches are created to increase roll-off, then out of band rejection is improved, but interference from adjacent RF communication bands is introduced due to excessive flyback
Solution Approach 1:
The second RF filter path serves as an intermediary that creates the stopband without directly interacting with the passband signals. By coupling the second filter path to the first rather than directly inserting notch filters into the passband path, the system achieves out of band rejection while the intermediary structure prevents excessive flyback that would otherwise cause interference from adjacent RF communication bands.
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 approach enhances out-of-band rejection with reduced ripple variation and flyback, improving power transfer efficiency and reducing interference between RF communication bands.
Implementation Method 1
a first RF filter path connected between a first port and a second port and including at least a pair of weakly coupled resonators, where the weakly coupled resonators are configured such that a first transfer response between the first port and the second port defines a first passband
Implementation Method 2
a second RF filter path coupled to the first RF filter path and configured such that the first transfer response between the first port and the second port defines a stopband adjacent to the first passband
Data Source
AI summary
Embodiments of radio frequency (RF) filtering circuitry are disclosed. In one embodiment, the RF filtering circuitry includes a first port, a second port, a first RF filter path, and a second RF filter path. The first RF filter path is connected between the first port and the second port and includes at least a pair of weakly coupled resonators. The weakly coupled resonators are configured such that a first transfer response between the first port and the second port defines a first passband. The second RF filter path is coupled to the first RF filter path and is configured such that the first transfer response between the first port and the second port defines a stopband adjacent to the first passband without substantially increasing ripple variation of the first passband defined by the first transfer response.