Frequency-Translatable Impedance Filter for RF Blocker Attenuation
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Solution Overview
Problem
Current communication systems face challenges in minimizing unwanted intermodulation components due to non-linear circuit blocks in RF transceivers, particularly in direct conversion receivers, where blockers can significantly degrade receiver performance and require high linearity mixers that are impractical due to design and cost constraints.
Innovation Solution
The implementation of a frequency translatable impedance (FTI) filter system that precedes the mixers to attenuate blockers, allowing for the use of mixers with relaxed linearity requirements by translating the impedance of frequency selective circuits, thereby reducing the power of blockers relative to the wanted channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high linearity mixers are used to minimize intermodulation components, then receiver performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by placing a filter before the mixer to attenuate blockers and reduce the power of unwanted signals before they reach the mixer. This pre-processing of the signal reduces the linearity requirements of the mixer, allowing the use of less complex and less expensive mixers while still achieving good receiver performance.
Solution Approach 2:
The patent introduces an intermediary filter between the antenna/receiver front-end and the mixer. This filter acts as a mediator that removes harmful intermodulation components and blockers before they can affect the mixer's operation, thereby protecting the mixer from requiring high linearity specifications.
2Reliability
If external high-Q filters are used to attenuate blockers, then receiver performance is improved, but device complexity increases
Solution Approach 1:
The patent merges the filter function with the mixer's existing structures and components. Instead of using separate external high-Q filters, the filter is integrated into the mixer circuitry, combining multiple functions into a single unit and reducing overall device complexity while maintaining effective blocker attenuation.
Solution Approach 2:
The patent creates a multi-functional structure that serves both as a filter and as part of the mixer circuitry. The integrated structure performs multiple functions including filtering, mixing, and impedance matching, thereby eliminating the need for separate external filters and reducing device complexity.
Data Source
AI summary
A system includes an input node, a frequency translatable impedance (FTI) filter, and a radio frequency (RF) downconverter module. The input receives an input signal having first and second components. The FTI filter filters the second components. The RF downconverter module receives the first components and downconverts the first components. Both the FTI filter and the RF downconverter module communicate with the input node.