Multi-Channel Radar Phase Calibration for Accurate Beamforming
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Solution Overview
Problem
In multi-receiver FMCW radar systems, achieving accurate phase calibration across multiple receiver chips is challenging due to phase offsets, which affect beamforming measurements and angle of arrival determination without proper calibration.
Innovation Solution
A phase calibration circuit and method utilizing a single local oscillator reference and built-in-test circuitry, including phase shifters, multi-frequency nonlinear phase detection, and power coupling circuits, to adjust and reduce phase offsets between multiple radar receiver chips through a negative feedback loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple receiver chips are used to provide beamforming capability, then the radar system's functionality is improved, but phase offsets between chips cause measurement errors
Solution Approach 1:
The patent implements a phase calibration circuit that uses feedback to measure and correct phase offsets between multiple receiver chips. The circuit injects test signals, measures the actual phase relationships, and adjusts the receivers accordingly to eliminate measurement errors in angle of arrival determination.
Solution Approach 2:
The patent introduces an intermediary phase calibration circuit that mediates between the multiple receiver chips and the signal processing system. This circuit includes signal injection paths and measurement mechanisms that indirectly assess and correct phase relationships without requiring direct modification of the receiver chips themselves.
2Measurement precision
If phase calibration circuitry is added to correct phase offsets, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the phase calibration functionality with the existing receiver structure by integrating signal injection paths and phase measurement mechanisms into the available circuitry. The calibration circuit reuses existing components where possible, combining calibration and operational functions to minimize overall complexity.
Solution Approach 2:
The phase calibration circuit is designed to be self-contained, injecting its own test signals and performing autonomous phase measurements and adjustments. The circuit calibrates itself without requiring external intervention or additional complex control systems, reducing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces phase offsets, ensuring accurate beamforming and angle of arrival measurements by converging the phase calibration circuit in a negative feedback loop, thereby improving the precision of radar signal processing.
Implementation Method 1
a phase detection circuit receiving the output signal B from the first signal splitter and the output signal C from the second signal splitter, the phase detection circuit comprising a phase detection circuit output signal that is related to a phase difference between the signal B and the signal C
Implementation Method 2
converging in the negative feedback loop whereby phase offset is reduced
Data Source
AI summary
This invention describes circuits and methods which can allow multiple radar receiver chips to be adjusted to have very low phase offset between them. Multiple receiver chips are used in frequency-modulated carrier-wave (FMCW) radar systems for beamforming to enable angle-of-arrival measurements. FMCW radar systems are widely used in collision-avoidance and adaptive cruise control systems in vehicles, which today are operating in the 76-81 GHz frequency band. In a multi-receiver system, each receive element must have a well-controlled phase response which can be calibrated over process, voltage, and temperature. Without calibration, phase offsets can result in erroneous beamforming receiver measurements. The inventive circuit provides a technique to adjust the phase of multiple receivers across multiple chips using a single local oscillator reference and built-in-test circuitry which consist of phase shifters, a multi-frequency nonlinear phase detection circuit, and power coupling circuits.