Contour Tuning Circuit With Tunable Notch Harmonic Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current RF systems face challenges in efficiently filtering out harmonics without degrading receiver signals, particularly in carrier aggregation scenarios, where tuned elements can regenerate harmonics and limit the harmonic floor, and existing solutions require multiple dedicated filters leading to increased cost and space constraints.
Innovation Solution
A tunable notch filter with a series LC circuit in parallel with a tunable capacitance circuit, integrated with an antenna switch, provides adjustable impedance to reject second harmonics by creating a parallel resonance, effectively shorting the tuning element at the harmonic frequency and reducing voltage swing across switches, thereby improving harmonic rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple dedicated filters are used to filter harmonics, then harmonic rejection is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a single filter structure that performs multiple functions: it filters harmonics across multiple frequency bands simultaneously and provides adjustable impedance matching for different signal paths. The controllable impedance element allows the same filter to be tuned for different operating conditions, eliminating the need for multiple dedicated filters for different bands.
Solution Approach 2:
The patent introduces a controllable impedance element (such as a variable capacitor or switchable component) that dynamically adjusts the filter's characteristics based on the operating mode. This dynamic adjustment allows the filter to adapt to different frequency bands and impedance requirements, providing harmonic rejection equivalent to multiple fixed filters while using a single dynamic structure.
2Object-affected harmful factors
If tuned elements are used to filter harmonics, then harmonic rejection is improved, but insertion loss increases
Solution Approach 1:
The patent changes the impedance parameter of the filter elements dynamically to optimize performance. By adjusting the impedance of the controllable element, the filter can achieve deep harmonic rejection at specific frequencies while maintaining low insertion loss in the passband. The impedance transformation capability allows the filter to present different characteristics at harmonic frequencies versus fundamental frequencies.
3Adaptability or versatility
If multiple filters are implemented for different frequency bands, then adaptability to multiple bands is improved, but area of the device increases
Solution Approach 1:
The patent designs a universal filter structure that can handle multiple frequency bands through impedance control rather than requiring separate physical filters for each band. The same filter topology serves multiple bands by dynamically adjusting its impedance characteristics, significantly reducing the total area required compared to having dedicated filters for each frequency band.
4Adaptability or versatility
If antenna switch states change, then signal path flexibility is improved, but impedance matching becomes more difficult
Solution Approach 1:
The patent incorporates controllable impedance elements that dynamically adjust to maintain impedance matching as the antenna switch changes states. When the switch transitions between different signal paths, the controllable impedance element compensates for the impedance variations, ensuring consistent matching performance across all switch states without requiring separate matching networks for each path.
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 achieves low insertion loss for desired carriers while introducing significant rejection at harmonic frequencies, addressing the limitations of existing systems by providing tunability in large signal environments and reducing the need for multiple filters.
Implementation Method 1
The series LC circuit can be inductive at frequencies above a resonant frequency of the series LC circuit so as to create a parallel resonance with the tunable capacitance circuit
Data Source
AI summary
Aspects of this disclosure relate tuning an impedance presented to a common port of a multi-throw switch and a tunable notch filter coupled to the common port. The impedance presented to the common port can be tuned based on an impedance associated with a throw of the multi-throw switch that is activated. According to embodiments of this disclosure, a shunt inductor in parallel with a tunable capacitance circuit can tune the impedance presented to the common port of the multi-throw switch. In certain embodiments, the tunable notch filter includes a series LC circuit in parallel with a tunable impedance circuit.