A TRL Error-box Split Procedure to Compensate for the Bias Dependency Effects in Device Test-Fixtures

In this paper we present a method to alleviate the errors introduced by the bias dependency of the electrostatic discharge or antenna-effect protection diodes when a direct metal-one TRL calibration is employed. The proposed method shows that the two error-boxes produced by the TRL algorithm can be split and combined without introducing mathematical errors as long as the perturbation can be assumed to be a reciprocal network. A mathematical analysis is provided and initially bench marked against a circuit level simulation employing only s-parameter defined error boxes and ideal lumped components and after verified using 3D EM simulations of the test fixtures. The circuit level simulator confirms the mathematical analysis while the 3D EM simulator validates the applicability in a more realistic setting. Finally, the proposed method is used in a real measurement where the test fixture are implemented in a 28nm CMOS technology and characterized at frequencies between 140 GHz to 200 GHz. The measurement using the proposed method clearly shows reduced deviation from known reference when compared to the non-split approach.