RF ADC Spur Cancellation Using Coherent Averaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Network test devices face challenges in effectively attenuating continuous wave spurs in digitized outputs from RF ADCs, particularly in high-density multiple transceiver designs, where traditional solutions require complex hardware and knowledge of multiple LO frequencies.
Innovation Solution
The implementation of a spur cancellation method based on frequency planning with coherent averaging, which converts continuous wave spurs into periodic signals, allowing for their attenuation without exact frequency value knowledge, using a combination of coherent averaging, shift registers, and digital frequency conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional hardware-based spur cancellation methods are used, then spur attenuation can be achieved, but device complexity and hardware requirements increase significantly
Solution Approach 1:
The patent replaces traditional hardware-based spur cancellation mechanisms with a digital signal processing approach. The receiver uses digital filtering and frequency domain processing to cancel spurs, eliminating the need for complex analog hardware circuits while achieving the same spur attenuation function.
Solution Approach 2:
The patent introduces an intermediary digital processing stage between the RF ADC and the baseband processing. This intermediary uses frequency domain analysis and filtering to identify and remove spur components, acting as a mediator that simplifies the overall system architecture while maintaining effective spur cancellation.
2Productivity
If multiple LO frequencies are used in high-density transceiver designs, then communication capacity increases, but spur generation and isolation requirements worsen
Solution Approach 1:
The patent extracts and removes spur components from the received signal using digital signal processing. By identifying spur frequencies and applying targeted filtering in the frequency domain, the system separates harmful spur components from the desired signal, enabling high-density transceiver operation without being constrained by traditional isolation requirements.
Solution Approach 2:
The patent converts the presence of spurs, which are normally harmful, into a manageable characteristic through frequency domain analysis. By identifying spur patterns and using coherent averaging techniques, the system transforms the harmful effect into a detectable and removable artifact, allowing multiple LO frequencies to coexist without interference.
3Measurement precision
If exact frequency values of multiple LOs are required for spur cancellation, then cancellation precision improves, but system complexity and information requirements increase
Solution Approach 1:
The patent implements a self-service approach where the receiver automatically identifies and characterizes spur frequencies through frequency domain analysis. The system uses the received signal itself to determine spur locations and characteristics, eliminating the need for external provision of LO frequency information while maintaining high cancellation precision.
Solution Approach 2:
The patent employs feedback mechanisms where the receiver continuously monitors the frequency domain representation of the received signal, identifies spur components, and adjusts filtering parameters accordingly. This closed-loop approach maintains precise spur cancellation without requiring a priori knowledge of LO frequencies, as the system adapts based on observed signal characteristics.
Data Source
Figure 1
Figure 2
Figure 3
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.