Multipath Bandpass Filter Notches for In-Band Blocker Removal
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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 frequencies, which is crucial for advanced communication systems like 5G NR, especially in wideband and ultra-wideband transceiver architectures, where in-band blockers need to be removed and frequency channels need to be aggregated.
Innovation Solution
A multipath bandpass filter with passband notches is designed, featuring multiple filter circuit branches connected in parallel, each comprising a downconverter, a filter network with low pass and notch filters, and an upconverter. This configuration allows for the attenuation of out-of-band frequencies and specific in-band channels by controlling the location of passband notches, using double-in double-switched downconverters to reduce timing constraints and improve harmonic suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional bandpass filter is used, then out-of-band frequencies are attenuated, but specific in-band frequencies cannot be selectively attenuated
Solution Approach 1:
The filter is divided into multiple parallel filter paths (e.g., four paths), each with its own downconverter, filter network, and upconverter. Each path processes a different frequency segment, allowing selective attenuation of specific in-band frequencies while maintaining the overall bandpass characteristic. This segmentation enables independent control of frequency response at different segments of the passband.
Solution Approach 2:
The filter employs dynamically controllable components including variable gain amplifiers, programmable filter networks, and phase shifters that can be adjusted in real-time. This dynamic control allows the filter to adapt its frequency response, enabling selective attenuation of specific in-band frequencies while maintaining flexibility for different filtering requirements.
2Manufacturing precision
If multiple filter paths are used to achieve frequency selectivity, then in-band frequency control is improved, but device complexity increases
Solution Approach 1:
Each filter path is designed as a universal module containing a downconverter, filter network, gain amplifier, and upconverter that can process any frequency segment. This multi-functional design allows the same circuit topology to be reused across multiple paths, reducing design complexity while achieving precise frequency response control through programmable filter networks and gain control.
Solution Approach 2:
The filter incorporates feedback mechanisms including phase detectors, error amplifiers, and programmable control logic that monitor and adjust the output of each filter path. This feedback enables precise control of the frequency response by dynamically adjusting gain, phase, and filter parameters to achieve the desired frequency selectivity and attenuation characteristics.
3Object-affected harmful factors
If in-band frequency attenuation is added, then blocker removal capability is improved, but signal quality of desired frequencies may deteriorate
Solution Approach 1:
The filter applies different filtering characteristics to different frequency segments within the passband. Each filter path is configured with specific attenuation levels and frequency responses tailored to the local requirements of that frequency segment. This local quality approach ensures that blockers are attenuated in specific frequency regions while desired signals in other regions maintain their quality without unnecessary attenuation.
Solution Approach 2:
The filter uses dynamically controllable gain amplifiers and programmable filter networks that can adjust their parameters in real-time based on the detected signal characteristics. This dynamic adaptation allows the filter to selectively attenuate blockers when present while maintaining full gain for desired signals, thereby preserving signal quality while removing interference.
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.