On-chip S11 signal detection circuit

As the RF era is ubiquitous nowadays, scattering parameters play an essential role in the modeling and verification of a variety of devices, chips, packages and transmission lines. To reduce the excessive cost in production chip testing with vector network analyzers (VNA), this paper proposes a simple system, utilizing only two lumped directional couplers (DC) and one power divider (DIV), that enables the measurement of the S₁₁ of the device-under-test (DUT) using power and phase detectors. The proposed system is fabricated in the 0.18-um IBM 7RF process with 1.60 mm width and 1.40 mm length die dimensions including the pads. Power and phase detectors can be cascaded in the system to increase the level of integration. The three-port system has a targeted operating frequency of about 10 GHz when all the devices are correctly tuned. The measurement results show the expected behavior at the targeted frequency but inaccuracy occurs away from this frequency. To extend the working frequency band, three types of calibration methods are proposed and verified through simulation. In addition, ad-hoc production testing can still work with this device by using the simple mapping, derived from comparing a measured golden DUT behavior to its pre-characterized behavior.