Phase Rotator Error Measurement Using I/Q Path Isolation
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Solution Overview
Problem
Existing radar systems face challenges in accurately determining and correcting phase errors caused by impairments such as leakage in mixers and multipliers, gain/amplitude imbalance, and phase imbalance between I and Q paths in phase rotators, which degrade radar performance and are critical for safe operation in applications like automotive collision detection.
Innovation Solution
A method and device for determining phase error by forcing the Q or I path of the phase rotator to zero, obtaining measurement sequences, forming shifted value pairs, and calculating actual phase values using arctan functions to compare with reference values, setting a warning flag if errors exceed a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase rotator is used for beam steering control, then radar performance is improved, but phase errors from impairments degrade the performance
Solution Approach 1:
The patent applies preliminary action by measuring and storing the actual phase response of the phase rotator across all phase codes before normal operation. This pre-characterization data is then used to compensate for phase errors during beam steering, eliminating the need for real-time error correction and maintaining high reliability while achieving precise phase control.
Solution Approach 2:
The patent implements feedback by measuring the actual phase output of the phase rotator for each phase code and using this measured information to correct subsequent phase control. The system compares the desired phase with the actual phase and applies compensation to eliminate errors, ensuring both high reliability and precision.
2Device complexity
If simple phase monitoring is used, then device complexity is reduced, but measurement precision of phase error is insufficient
Solution Approach 1:
The patent applies self-service by using the phase rotator's own output signal to measure its phase characteristics. The system feeds the phase rotator output back through the antenna array and uses the received signal to determine actual phase values, eliminating the need for external calibration equipment and keeping the monitoring system simple while achieving high measurement precision.
3Measurement precision
If multiple impairments are present in phase rotator, then phase error increases, but identifying individual contributors becomes complex
Solution Approach 1:
The patent applies segmentation by measuring the phase rotator's response to each phase code independently and storing separate measurement values for each code. This breaks down the complex multi-source phase error into individual measurable components, allowing precise identification of each contributor without requiring complex real-time analysis of combined effects.
Data Source
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AI summary
There is described a method of determining phase error caused by impairments in a phase rotator, said impairments including leakage in mixers and/or multipliers of the phase rotator, gain/amplitude imbalance and a known phase imbalance between an I path and a Q path in the phase rotator, the phase rotator having an input for receiving a reference phase value, a local oscillator and circuitry configured to provide an output signal with a phase corresponding to the reference phase value. The method comprises (a) forcing the Q path of the phase rotator to zero and obtaining a first sequence of successive measurement values indicative of a power of the phase rotator output signal, each successive measurement value in the first sequence corresponding to one of a plurality of successive reference phase values, (b) forcing the 1 path of the phase rotator to zero and obtaining a second sequence of successive measurement values indicative of the power of the phase rotator output signal, each successive measurement value in the second sequence corresponding to one of the plurality of successive reference phase values, (c) forming a sequence of successive measurement value pairs, each measurement value pair comprising one measurement value from the first sequence of successive measurement values and one measurement value from the second sequence of successive measurement values, wherein the first sequence of successive measurement values is shifted relative to the second sequence of successive measurement values by an amount corresponding to the known phase imbalance, (d) calculating an actual phase value for each of the successive measurement value pairs, and (e) determining the phase error by comparing the actual phase values with the corresponding reference phase values. Furthermore, a corresponding device and a radar system comprising such a device are described.