An ISO 26262 compliant built-in self-test for 77 GHz automotive radar sensors

More and more applications and a steadily increasing market penetration are showing the success of radar based driver assistance systems. While in recent years most of those systems were focussing on the advance of the drivers´ comfort, today many safety applications are offered. As those systems can directly influence the vehicle dynamics, functional safety in terms of new normative requirements, such as the ISO 26262 is gaining more interest. Therefore, in this paper a built-in self-test is presented which is able to monitor multiple receiver paths by measuring the amplitude and phase imbalance among all channels. Four different types of coupling elements to feed a test signal into receiver paths are investigated and evaluated in terms of their precision. Furthermore, a method for a baseband evaluation is proposed.