Design of a X-band image rejection balanced mixer

In order to meet the need of anti-interference in the millimeter wave receiver and radar, fundamental theory of the image rejection sub-harmonic mixer was introduced first, then a design proposal of a X-band image-rejection balanced mixer was proposed. The mixer is made up of two mixer units, RF signal and image signal can be distinguished by the phase relationship of the outputs from two units. The RF outputs of the two units are in-phase and combine, the image output of the two units are 90 phase difference and offset. Passive part simulation and harmonic balance simulation of the mixer were finished by the software HFSS and ADS, respectively. The mixer was finally fabricated and tested. The tested result shows that, when RF and IF are 9.3~9.7GHz and 100MHz respectively, the convention loss is about 8.8dB, the image rejection is larger than 17dB, all the port-to-port isolations are larger than 20dB, the voltage standing wave ratio(VSWR) of the RF port and LO port are less than 1.3 and 2.2 respectively, the input power 1dB compression point is 11.5dBm.