Analysis of HBT Vector Modulator Phase Shifters Based on Gilbert Cell for sub-THz Regimes
This paper concerns with the nonlinearity analysis and compensation of active phase shifters based on vector modulator topologies which utilize Gilbert cell type multipliers. In this respect, both frequency dependence and expansion behavior of such topologies are analyzed. Based on translinear circuits theory, log/anti-log nonlinear equations are transformed to algebraic linear equations and/or multiplication equations, which facilitates solution for such nonlinear equations. To validate the analyses, a 5-bit active phase shifter was designed and simulated in 0.13um HBT technology node. 3D electromagnetic simulation results verify the consistency of the analysis and proposed compensation technique.