Measuring the frequency response of poly-phase filters using standard laboratory equipment

This paper presents an effective technique for generating pairs of in-quadrature sinusoidal signals by using only standard signal generators and oscilloscopes. The proposed method is particularly well suited for measuring the magnitude characteristic of poly-phase filters. An example is presented in some detail: the characterization of a fully differential poly-phase filter integrated in a standard 0.18um CMOS process, which operates in the MHz range. The measurements are in good agreement with the simulation results.