Multipath Bandpass Filter Notches for In-Band Channel Rejection
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Solution Overview
Problem
Current radio frequency (RF) bandpass filters lack the ability to effectively attenuate both out-of-band and specific in-band frequency channels, which is crucial for advanced communication systems like 5G NR that require precise filtering to support carrier aggregation and reduce in-band blockers.
Innovation Solution
A multipath bandpass filter with passband notches is introduced, featuring multiple filter circuit branches connected in parallel, each comprising a downconverter, a filter network with low pass and notch filters, and an upconverter, allowing for the generation of a bandpass signal with controlled passband notches. This design uses double-in double-switched downconverters to manage clock signals of different phases, enabling flexible control over the center frequency and notch locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional RF bandpass filters are used, then out-of-band frequencies are attenuated, but specific in-band frequency channels cannot be selectively attenuated
Solution Approach 1:
The filter is divided into multiple parallel filter circuit branches (first branch, second branch, third branch, etc.), each capable of independently filtering different frequency channels. This segmentation allows selective attenuation of specific in-band frequency channels while maintaining the ability to attenuate out-of-band frequencies, thereby achieving frequency channel selectivity without requiring a completely different filter architecture.
Solution Approach 2:
Each filter circuit branch is designed with universal functionality to handle both out-of-band and in-band frequency filtering. The branches use identical structural components (downconverters, filter networks with low pass and notch filters, upconverters) that can be configured through clock signal phases to achieve different filtering objectives, making the system versatile for various frequency selection requirements.
2Manufacturing precision
If multiple discrete filters (SAW or BAW filters) are used to achieve precise filtering, then frequency channel selectivity is improved, but device complexity and cost increase
Solution Approach 1:
Multiple filtering functions that would traditionally require separate discrete filters (SAW or BAW filters) are merged into a single integrated filter circuit. The parallel filter circuit branches work together within one device to provide the frequency channel selectivity that would otherwise require multiple discrete components, thereby reducing device complexity and integration requirements while maintaining precise frequency filtering capability.
Solution Approach 2:
The filter circuit is designed as a universal structure that can perform multiple filtering functions simultaneously through its parallel branches. By configuring the clock signal phases and notch filter parameters, the same circuit can target different frequency channels for attenuation, eliminating the need for multiple dedicated filters for different frequency selections.
3Adaptability or versatility
If filter circuit branches operate simultaneously, then filtering coverage is improved, but signal quality may deteriorate due to interference
Solution Approach 1:
The filter circuit branches operate in a time-division manner using periodic switching controlled by clock signals with different phases. Instead of all branches operating continuously and simultaneously, they are activated periodically at different time instances, which reduces mutual interference between branches while maintaining comprehensive frequency coverage through the coordinated operation of all branches over time.
Data Source
AI summary
Apparatus and methods related to multipath bandpass filters with passband notches are provided herein. In certain configurations, a multipath bandpass filter includes multiple filter circuit branches or paths that are electrically connected in parallel with one another between an input terminal and an output terminal. The input terminal receives an input signal, and each filter circuit branch includes a downconverter that downconverts the input signal to generate a downconverted signal, a filter network that generates a filtered signal by filtering the downconverted signal, and an upconverter that upconverts the filtered signal to generate a branch output signal. The filter network includes at least one low pass filter and at least one notch filter to provide a passband with in-band notches. The branch output signals from the filter circuit branches are combined to generate an output signal at the output terminal.