On-chip “baluntennas” for differential-mode non-contact characterization of mmW/THz devices and ICs

We present a novel on-chip, lens-integrated differential-mode double-slot antenna structure to enable iso-lated, pure differential-mode signal injection and interrogation for on-wafer devices and integrated circuits. Testing of on-chip differential devices and circuits conventionally requires Marchand-type baluns integrated either with the device or with the dual-tip contact-probes. Nevertheless, these state-of-the-art balun-integrated probes can cover only up to 110 GHz. In this work, we demonstrate a 180°-hybrid “baluntenna” based on a novel on-chip antenna design that concurrently acts as a high isolation balun. The baluntenna is integrated with the device-under-test and a quasi-optical link is used to effectively couple test signals into and out of the on-wafer ports of the device under test. As such, this approach allows, for the first time, non-contact, pure differential-mode characterization of on-chip devices and integrated circuits at well beyond 100 GHz.