Simple, Analytical Expressions of an Effect of Local Signal Imperfections on Four-Phase Passive-Mixer-Based Bandpass Filter

This paper describes simple, analytical expressions for a quadrature passive-mixer-based RF bandpass filter. We have analyzed the passive mixer clocked by the trapezoidal-shaped local (LO) signals with different rise and fall times. Obtained results show that the partially overlapping LO signals and/or large capacitance of low-noise amplifier load cause charge reduction of each baseband branch capacitance. This results in the filter characteristics degradation. To achieve good filter characteristics, short rise and fall time of the LO signal and/or appropriate mixer RF-node biasing is effective. Our analysis results agreed well with the data obtained from the Advanced Design System simulator.