GIC N-Path Bandpass Filter for Wideband Jammer Rejection
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Solution Overview
Problem
Conventional N-path filters with single poles struggle to provide sufficient out-of-band rejection for wideband signals, especially in wireless communication networks, due to their narrow bandwidth and limited rejection capabilities for TX leakage and jammers.
Innovation Solution
The implementation of N-path filters with multiple concurrent passbands using impedance converters, specifically generalized impedance converter (GIC) circuits, which enhance the filter order and provide steeper rejection by incorporating second-order or higher impedances, and the use of gyrator circuits to simulate inductive elements, allowing for wider passbands and improved rejection of out-of-band signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional N-path filters with single poles are used, then the device complexity is low, but the out-of-band rejection is insufficient
Solution Approach 1:
The patent changes the pole order parameter from single pole to second-order or higher poles by incorporating bandpass response circuits with inductive and capacitive elements, thereby improving out-of-band rejection while managing device complexity through systematic design
Solution Approach 2:
The filter is segmented into multiple parallel branches (N-path structure) where each branch contains independent bandpass response circuits, allowing the system to achieve high rejection through collective action of multiple simpler units rather than one complex unit
2Reliability
If N-path filters with second-order or higher poles are implemented, then the out-of-band rejection improves, but the passband bandwidth becomes narrower
Solution Approach 1:
The patent uses time-varying switching arrangements that dynamically connect different impedance sections to the input signal path at different time intervals, creating an effective wide passband through temporal multiplexing of multiple narrower bandpass circuits
Solution Approach 2:
The patent extends the filter design from a single static frequency response to multiple dynamic frequency responses by adding the time dimension through periodic switching, allowing the filter to achieve wide effective bandwidth while maintaining high rejection at specific frequencies
3Adaptability or versatility
If multiple concurrent passbands are added to handle carrier aggregation, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The patent designs universal bandpass response circuits that can be configured to pass multiple different frequency bands by changing the switching timing and duration, allowing a single filter structure to serve multiple functions for different carrier aggregation scenarios
Solution Approach 2:
The patent employs periodic switching of impedance sections with different duty cycles to create multiple concurrent passbands, where each branch is activated periodically at different time intervals to allow different frequency components to pass through at different times
Data Source
AI summary
Certain aspects of the present disclosure provide an N-path filter implemented using a generalized impedance converter (GIC) circuit. The GIC circuit is configured such that the N-path filter has a desired frequency response, which may include a wide passband with steeper rejection than a conventional N-path filter with only a single pole in each filter path. Certain aspects of the present disclosure provide an N-path filter having a frequency response with multiple concurrent passbands. In certain aspects, the N-path filter with multiple passbands is implemented using the GIC circuit. In other aspects, the N-path filter may include a bandpass response circuit where an inductance of the bandpass response circuit may be implemented using gyrators.