Adaptive RF Filter Using Composite Inductors for Wideband Linearity
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Solution Overview
Problem
Existing adaptive filters, whether passive or active, face issues such as bulkiness, complexity, and insufficient linearity or high electrical consumption, making them unsuitable for wide frequency bands and certain applications.
Innovation Solution
An adaptive radio frequency filter combining fixed passive inductors with variable active inductors, optionally with negative resistors, to form variable composite inductors, allowing real-time reconfiguration of properties like bandwidth and cut-off frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If passive filters are used to achieve wide frequency band coverage, then the filter can operate over multiple frequency bands, but the bulk and complexity increase due to duplication of filter parts
Solution Approach 1:
The patent uses variable capacitors that can be dynamically adjusted to change the filter's characteristics in real-time, allowing a single filter structure to adapt to different frequency bands without physical duplication. This dynamic reconfiguration replaces the static need for multiple duplicate filter parts.
Solution Approach 2:
The filter design makes a single filter structure perform multiple functions across different frequency bands by using variable capacitors that can be tuned to different values, enabling one universal filter to replace what would traditionally require multiple specialized filters.
2Ease of manufacture
If passive filters are manufactured using silicon integration technologies, then manufacturing is simplified, but the quality factor becomes low leading to large insertion losses
Solution Approach 1:
The patent combines passive filter structures with active components (variable capacitors and negative resistors) to create a composite system that maintains the manufacturability of passive components while adding the beneficial properties of active components, specifically higher quality factor and lower insertion loss.
Solution Approach 2:
Negative resistors are introduced as intermediary components that compensate for the losses inherent in passive silicon-integrated filters. These negative resistors actively counteract the energy losses, effectively reducing insertion loss while maintaining compatibility with standard manufacturing processes.
3Adaptability or versatility
If active filters with variable active inductors are used, then the filter can be reconfigured in real-time, but the linearity performance becomes insufficient
Solution Approach 1:
The patent creates a hybrid composite system combining passive inductors (which provide good linearity) with variable active capacitors (which provide reconfiguration capability). This composite approach allows the filter to maintain the linearity benefits of passive components while gaining the adaptability of active components.
Solution Approach 2:
Negative resistors serve as intermediary components that compensate for the non-linearities and losses introduced by variable active inductors. By actively counteracting these detrimental effects, the system maintains good linearity performance while preserving real-time reconfiguration capabilities.
4Adaptability or versatility
If variable active inductors are used in active filters, then real-time adjustment is possible, but electrical consumption becomes high
Solution Approach 1:
The patent employs variable capacitors instead of variable inductors for real-time adjustment. Variable capacitors generally consume less power than variable active inductors while providing the same dynamic reconfiguration capability, thus reducing electrical consumption while maintaining adaptability.
Solution Approach 2:
Negative resistors are used as intermediary components that compensate for losses with minimal additional power consumption, enabling real-time adjustment through variable capacitors while keeping overall electrical consumption low compared to using variable active inductors.
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 filter achieves improved linearity and reduced bulk and insertion losses, enabling efficient switching across wide frequency bands with lower power consumption compared to conventional designs.
Implementation Method 1
Active filters include variable active inductors, i.e. active electronic circuits simulating the behavior of inductors, where such circuits can include elements such as gyrators and/or amplifiers.
Implementation Method 2
the radio frequency filter can also include a negative resistance associated with said at least one variable active inductor
Data Source
AI summary
An adaptive radio frequency including an input, an output, at least one fixed passive inductor and at least one variable active inductor connected between the input and the output.