Improved probing reliability in antenna-on-chip measurements

Antenna-on-Chip (AoC) measurements are mostly performed with on-wafer probes. The connection between the probe tips and antenna under test (AUT) plays a crucial role in influencing the measurement reliability. A tilted probe or a nonplanarly packaged AoC can result in floating pin(s) during the landing process of the probe. We have measured the behavior of the input reflection coefficient when a ground-signal-ground probe touches a SHORT calibration standard and the possible contact states are modeled, simulated, and compared with measurements. The analysis demonstrates that the probe will radiate as an antenna, which will make it almost impossible to determine the real AoC characteristics. To improve the probing reliability, it is necessary to determine a reference force to be applied to the AUT. We recommend adding an on-chip SHORT to be integrated with the AoC, which can be aligned with the test pads.