N-Path Gm-C Self-Interference Cancellation for Close-Band Transceivers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing techniques for cancelling interference between closely operating transmitters and receivers in wireless devices are inefficient, particularly as frequencies get closer together, affecting receiver performance in multi-band frequency division duplexing and full-duplex transceivers.
Innovation Solution
The implementation of RF high-Q bandpass filters that emulate the magnitude, phase, magnitude slope, and phase slope responses of antenna isolation in different sub-frequency bands, along with tunable and reconfigurable second-order N-path Gm-C filters, to provide self-interference cancellation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmitter and receiver operate in close frequency bands simultaneously, then wireless device functionality is improved, but receiver performance deteriorates due to interference
Solution Approach 1:
The frequency spectrum is divided into multiple sub-frequency bands, with dedicated RF high-Q bandpass filters for each band. This segmentation allows the system to process different frequency components separately, enabling selective cancellation of interference in specific bands while maintaining receiver operation in other bands.
Solution Approach 2:
The invention creates a replica of the transmit signal path including RF high-Q bandpass filters that copy the magnitude, phase, magnitude slope, and phase slope responses of the actual antenna isolation. This copied model is then used to generate cancellation signals that accurately match the interference characteristics across different frequency bands.
2Productivity
If frequencies of transmitter and receiver get closer together, then frequency utilization efficiency is improved, but interference cancellation difficulty increases
Solution Approach 1:
The RF high-Q bandpass filters are designed with tunable parameters including center frequency, bandwidth, and Q-factor that can be adjusted based on the specific frequency separation between transmitter and receiver. This allows the cancellation system to adapt to different frequency configurations and maintain effectiveness even when frequencies are very close together.
Solution Approach 2:
The system employs dynamically adjustable RF high-Q bandpass filters with variable resistance and capacitance elements that can be reconfigured in real-time. This dynamic capability allows the filters to track and adapt to changing frequency conditions, making the interference cancellation effective across a wide range of frequency separations.
3Measurement precision
If RF high-Q bandpass filters are used to emulate antenna isolation responses, then self-interference cancellation accuracy is improved, but device complexity increases
Solution Approach 1:
The RF high-Q bandpass filter circuit is designed to perform multiple functions simultaneously: filtering specific frequency bands, emulating antenna isolation responses, and generating cancellation signals. By making the filter multi-functional, the invention reduces the need for separate circuits for each function, thereby limiting the increase in overall device complexity.
Data Source
AI summary
Self-interference cancellers are provided. The self-interference cancellers can include multiple second-order, N-path Gm-C filters. Each filter can be configured to cancel self-interference on a channel of a desired bandwidth. Each filter can be independently controlled using a variable transmitter resistance, a variable receiver resistance, a variable baseband capacitance, a variable transconductance, and a variable time shift between local oscillators that control switches in the filter. By controlling these variables, magnitude, phase, slope of magnitude, and slope of phase of the cancellers frequency responses can be controlled for self-interference cancellation. A calibration process is also provided for configuring the canceller.