Loopback Testing of Automotive 77 GHz Antenna-in-Package Radar Transceiver ICs

In this contribution, a testing strategy is presented showing how automotive radar transceivers with packaged antennas can be measured in a metrologically reproducible way with regard to their high-frequency properties. The testing concept presented in this work is based on a full loopback from the 3 TX channels to the 4 RX channels of a single chip 77 GHz radar transceiver, TEF810X, manufactured by NXP Semiconductors. The concept uses a Printed Circuit Board (PCB) based structure to facilitate the coupling of the EM waves from the packaged antennas into waveguides. Thereafter, a fan out structure is designed in a metallic block with rectangular waveguides to increase inter-channel spacing of the individual TX and RX channels. Finally, another PCB is designed to facilitate the loopback from TX channels to RX channels using microstrip transmission lines. An insertion loss of roughly 5 dB, a return loss of roughly 19 dB and an inter-channel isolation of > 25 dB is achievable over a frequency range of 76 GHz - 81 GHz.