The third order intermodulation distortion analysis of microwave passive mixers in radar receivers

Microwave mixers are widely used in radar receivers as down-converting components, the dynamic range of which is one of the key parameters that determine the radar detecting performance. In this paper, the nonlinear behavior of the mixer is derived and depicted in the equations. It is obvious that the third order output intercept point (OIP3) of the mixer will be degraded by mismatching IF output impedance as well as changing the power levels of the RF and local oscillation (LO). It is what often happens in the practical RF system. The analysis is proved by the following simulation and measurement. This result will be valuable for designers to design and debug their receivers.