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 such nonlinear equation solving. To validate the analyses, a 5-bit active phase shifter was designed in 0.13um HBT technology and simulated. Simulation results verify the analysis and compensation technique within less than 10% discrepancy.