Receiver Spur Cancellation Using Coherent Averaging
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Solution Overview
Problem
Network test devices face challenges in attenuating continuous wave spurs in digitized RF signals due to the large bandwidth of RF ADCs, which leads to desensitization and requires complex hardware designs for isolation, limiting the operating range and integration density.
Innovation Solution
The implementation of a spur cancellation technique based on frequency planning with coherent averaging, which converts spur signals into periodic signals, allowing for efficient attenuation without requiring knowledge of exact LO frequencies, and compensates frequency errors through digital frequency conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complex hardware designs for isolation are used to attenuate continuous wave spurs, then spur attenuation is improved, but device complexity increases and integration density is limited
Solution Approach 1:
The patent replaces complex hardware isolation mechanisms with a digital signal processing approach. A spur cancellation block processes the digitized RF signal to identify and remove continuous wave spurs through digital filtering and signal cancellation techniques, eliminating the need for complex analog isolation hardware while achieving equivalent or superior spur attenuation performance
Solution Approach 2:
The patent changes the operating parameters of the RF ADC to optimize spur attenuation. By adjusting the sampling rate, resolution, and frequency range parameters, the system achieves better spur rejection without requiring complex hardware isolation, thereby reducing device complexity while maintaining effective spur attenuation
2Object-affected harmful factors
If complex hardware designs for isolation are used to attenuate continuous wave spurs, then spur attenuation is improved, but isolation requirements become more stringent
Solution Approach 1:
The patent substitutes digital signal processing for analog isolation hardware, thereby relaxing isolation requirements. The spur cancellation block processes signals digitally after ADC conversion, eliminating the need for stringent analog isolation between RF components while achieving effective spur attenuation
3Productivity
If the full operating range of RF ADCs is utilized, then productivity is improved, but continuous wave spurs cause desensitization
Solution Approach 1:
The patent extracts and removes continuous wave spurs from the digitized RF signal using a dedicated spur cancellation block. This allows the system to utilize the full operating range of the RF ADC without desensitization, as the harmful spurs are identified and eliminated through digital signal processing while preserving the desired signal content
Solution Approach 2:
The patent employs feedback mechanisms in the spur cancellation block to continuously monitor and adjust the cancellation of continuous wave spurs. By feeding back the processed signal information, the system maintains optimal spur attenuation across the full ADC operating range, enabling productive utilization without desensitization effects
Data Source
AI summary
In some implementations, a receiver may obtain a digitized output of a radio frequency (RF) analog-to-digital-converter (ADC) of the receiver. The receiver may apply a spur cancellation to the digitized output of the RF ADC to attenuate one or more continuous wave spurs from the digitized output of the RF ADC, wherein the spur cancellation is based on a frequency planning with coherent averaging.