Concurrent Circuit-Level/System-Level Optimization of a 24 GHz Mixer for Automotive Applications Using a Hybrid Electromagnetic/Statistical Technique

The successful use of the design of experiments (DOE) and response surface methods (RSM) approaches in the simultaneous optimization of geometrical parameters and power requirements of a 24 GHz mixer is presented. The benchmarking geometry is a low-cost mixer for a Doppler radar sensor, built in liquid crystal polymer (LCP) technology. First, the single-balanced diode mixer is designed for good RF/LO isolation and low conversion loss. The structure is then optimized using the same experiment that integrates both geometrical parameters and the LO input power levels. The optimized mixer shows a 4.5 dB conversion loss with a 23 dB isolation between RF and LO ports at the operating input power levels, the best reported so far for this frequency range and in these operating conditions.