RF Spur Cancellation Using Feedback-Tuned Clock Spur Removal
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Solution Overview
Problem
Current RF receiver integrated circuits face challenges in eliminating spurs caused by digital clock signals, especially when multiple receive paths are involved, as frequency planning becomes impractical for certain channel combinations, leading to interference within tuned channels.
Innovation Solution
A spur cancellation system that utilizes a spur cancellation module to generate a cancellation signal with known frequency and estimated parameters, adjusting amplitude, phase, and frequency using digital feedback to effectively remove spurs from digital information processed by the RF receiver, and employs multiple modules for each receive path to handle multiple spur sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency planning is used to adjust digital clock frequencies to avoid spurs, then spur interference is reduced, but device complexity and difficulty of implementation increase significantly
Solution Approach 1:
The system generates a cancellation signal that is the inverse of the expected spur signal before the spur interferes with the received channel. By predicting the spur characteristics based on known clock frequencies and generating the opposite signal in advance, the system prevents spur interference without requiring complex frequency planning adjustments.
Solution Approach 2:
Instead of trying to avoid or eliminate the digital clock spurs through frequency planning, the system converts the harmful spur signals into a useful cancellation mechanism. The spurs are detected, characterized, and then used to generate an inverse cancellation signal that actively removes them from the received channel, turning the harmful interference into a beneficial filtering process.
2Adaptability or versatility
If multiple receive paths are included to tune multiple channels simultaneously, then channel tuning capability is improved, but frequency planning becomes practically impossible for certain channel combinations
Solution Approach 1:
The system segments the spur cancellation function into individual modules for each receive path. Each receive path has its own spur cancellation module that independently processes spurs from its associated digital clocks. This modular approach allows multiple channels to be tuned simultaneously without requiring global frequency planning coordination, as each path handles its own interference independently.
Solution Approach 2:
The spur cancellation module is designed as a universal solution that can handle multiple spur sources and multiple receive paths through a common architecture. The same cancellation mechanism works for single-channel and multi-channel scenarios, eliminating the need for different frequency planning approaches for different channel configurations.
3Stability of the object's composition
If digital clocks operate at fixed frequencies for stable timing, then timing stability is improved, but spur frequencies fall within broadcast channels causing interference
Solution Approach 1:
The system introduces a cancellation signal as an intermediary element between the digital clock and the received channel. Rather than changing the clock frequency to avoid spurs, the cancellation signal acts as a mediator that captures and neutralizes the spur interference, allowing the clock to maintain its stable fixed frequency while preventing the spurs from affecting the broadcast channel.
Data Source
AI summary
Spur cancellation systems and related methods are disclosed for radio frequency (RF) receivers and other implementations. Disclosed embodiments effectively remove spurs caused by digital clock signals or other spur sources by determining which spurs will fall within a channel selected to be tuned, utilizing a spur cancellation module to generate a cancellation signal, and subtracting this cancellation signal from the digital information. The cancellation signal can be initially generated with a known frequency and estimated values for unknown spur parameters, such as amplitude and phase. Digital feedback signals are then used to adjust the spur parameters. If the spur frequency is not known precisely, digital feedback signals can also be used to adjust the frequency of the cancellation signal. Where multiple receive paths are provided within a multi-receiver system, multiple spur cancellation modules can be used to remove spurs generated by digital clocks within each of the receive paths.