Selective RF Attenuation Paths for Accurate mmWave Gain-Phase Calibration
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Solution Overview
Problem
Testing RF signal processing chains at mm wave frequencies, such as those used in 5G communication, is costly and difficult due to the challenge of ensuring that gain/phase detectors used for measurement are more accurate than the signal processing chains they measure, and the need for precise gain and phase calibration in transceivers is hindered by high signal power differences and cross-talk.
Innovation Solution
An attenuator arrangement with differential paths and cascode switching circuits that selectively attenuate signals based on relative power levels, using a controller to manage selector signals and attenuator ladders to equalize signal power, thereby improving measurement accuracy and reducing cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain/phase detectors are used to measure signal processing chains at mm wave frequencies, then measurement capability is provided, but measurement precision deteriorates due to the difficulty of ensuring detectors are more accurate than the signal processing chains they measure
Solution Approach 1:
The patent introduces an attenuator as an intermediary component between the signal processing chain and the gain/phase detector. This attenuator reduces the signal power level to a suitable range for accurate measurement, enabling the detector to operate in its optimal measurement range and achieve higher measurement precision without requiring the detector to be inherently more accurate than the signal processing chain itself
Solution Approach 2:
The patent changes the power parameter of the signal by introducing variable attenuation. By adjusting the attenuation level, the signal power is transformed from a potentially overwhelming level to one that is suitable for accurate detection, thereby improving measurement precision through parameter transformation rather than requiring more complex or accurate detection equipment
2Power
If high signal power levels are used in transceiver calibration, then signal strength is sufficient for measurement, but cross-talk increases and measurement accuracy deteriorates
Solution Approach 1:
The patent employs a variable attenuator that can dynamically adjust its attenuation level based on the signal power conditions. This dynamic adjustment capability allows the system to optimize the balance between maintaining sufficient signal strength for measurement and reducing cross-talk interference, thereby resolving the contradiction between signal power and cross-talk
Solution Approach 2:
The patent implements a feedback mechanism where the measurement apparatus monitors the signal conditions and the attenuator adjusts its attenuation level accordingly. This closed-loop control enables the system to automatically optimize the signal power level to minimize cross-talk while maintaining adequate signal strength for accurate calibration measurements
3Measurement precision
If signal power levels are equalized for accurate measurement, then measurement precision improves, but additional attenuation control mechanisms increase device complexity
Solution Approach 1:
The patent divides the attenuation control into discrete, selectable attenuation levels rather than requiring continuous variable control. This segmentation of the attenuation function into distinct steps simplifies the control circuitry while still achieving sufficient signal power equalization for accurate measurement, reducing the complexity compared to fully continuous control mechanisms
Data Source
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AI summary
An attenuator arrangement comprising at least a first attenuation path configured to couple between a signal processing chain, SPC, and a measurement apparatus; said SPC comprising a first and second SPC terminal, said SPC configured to apply one or both of a gain and phase change on a signal passed between the SPC terminals; said measurement apparatus configured to measure one or both of the gain and the phase change applied by SPC by coupling to and receiving signals from said SPC terminals; wherein one of said first SPC terminal and said second SPC terminal is coupled to the measurement apparatus through said first attenuation path; and wherein the at least first attenuation path of the attenuator arrangement is configured to provide, selectively, for attenuation of the signal to the measurement apparatus to make the signal power of the signals from said SPC terminals more equal.