Radar Receiver Self-Test Using Successive Chirp Path Comparison
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Solution Overview
Problem
Current built-in self-test (BIST) systems for mmW radar units are inadequate in detecting transient faults and require intrusive methods, which can lead to false positives/negatives and increased complexity, especially in automotive safety-critical systems where functional safety is paramount.
Innovation Solution
A non-intrusive BIST system that utilizes real radar signals, specifically chirp echo signals, to estimate linearity parameters of ADCs and other components within the receiver chain by applying DC offsets or filtering, allowing for concurrent testing without interrupting normal operation and eliminating the need for dedicated signal generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plausibility checks are implemented to detect safety-relevant defects, then the ability to detect faults is improved, but false-positive or false-negative decisions occur and the system complexity increases
Solution Approach 1:
The radar receiver performs self-testing by processing its own received signals through multiple paths with different DC offsets or filter responses. The receiver circuit itself generates the test data by comparing outputs from different signal processing paths, eliminating the need for external test equipment and complex plausibility check implementations.
Solution Approach 2:
The receiver circuit is designed to perform both normal signal processing and self-testing functions using the same hardware components. The multi-path configuration with DC offset injection or filtering allows the receiver to simultaneously maintain its primary function while embedded safety monitoring capabilities, reducing overall system complexity.
2Measurement precision
If dedicated test signal generators are used for BIST, then testing accuracy is improved, but hardware complexity and cost increase
Solution Approach 1:
The receiver circuit serves dual purposes: normal radar signal reception and self-testing. By configuring the receiver to process signals through multiple paths with different DC offsets or filter responses, the same hardware generates the necessary test data without requiring dedicated signal generators or external test equipment.
Solution Approach 2:
The receiver performs self-testing by utilizing its own received signals and processing them through multiple configured paths. The system monitors itself by comparing outputs from different processing paths, eliminating the need for separate test signal generation hardware.
3Productivity
If ADC conversion rate is increased to improve testing, then testing frequency is improved, but ADC performance decreases and current consumption increases
Solution Approach 1:
The self-testing is performed periodically by intermittently applying different DC offsets or filter configurations to the received signal paths. This periodic switching allows the system to conduct multiple measurements over time without requiring a continuously high conversion rate, thereby maintaining ADC performance while achieving thorough testing.
4Reliability
If multiple ADCs are used for comparison testing, then fault detection capability is improved, but hardware overhead increases
Solution Approach 1:
The signal processing is divided into multiple paths within the same ADC, where each path applies different DC offsets or filter responses. This segmentation allows comparative testing of different signal processing configurations using a single ADC, avoiding the need for multiple ADCs while maintaining fault detection capability.
Data Source
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AI summary
A radar unit (100, 300) is described that comprises: a frequency generation circuit (103, 106, 303, 306) configured to generate a millimetre wave, mmW, frequency modulated continuous wave, FMCW, transmit signal comprising a plurality of chirps; a transmitter circuit (108, 102, 308, 302) configured to transmit the generated mmW FMCW transmit signal: a receiver circuit (104, 110, 304, 310) configured to receive an echo of the mmW FMCW transmit signal; and a built-in self-test, BIST, circuit (140, 340) coupled to the receiver circuit (104, 110, 304, 310) and configured to process the echo of the mmW FMCW transmit signal. The receiver circuit (104, 110, 304, 310) is configured to operate with at least two different paths for at least two successive chirps of the mmW FMCW transmit signal and create therefrom at least two respective received chirp signals; and the BIST circuit (140, 340) is configured to process and compare the at least two respective received chirp signals and determine therefrom an operational state of at least one circuit or component within the receiver circuit (104, 110, 304, 310).