Design of a single balanced diode mixer with high LO/RF and LO/IF isolation in C-band test loop translator

The design and analysis of a LO/RF and LO/IF isolation and conversion loss in a single balanced diode mixer are presented in this paper. The single balanced diode mixer is realized by using a configuration of a 90 degree hybrid coupler and two HSMS282C GaAs Schottky diodes. A single balanced diode mixer with band pass filter is one of common devices used in microwave receivers. The mixer operates in C-band. It down converts the block of frequencies (6.72 – 7.02 GHz) to a block of frequencies (4.5 – 4.8 GHz) by local oscillator of signal frequency of 2.22 GHz. The proposed mixer achieves the double balanced functionality with the help of single balanced diode and avoids the need of RF and LO baluns. The conversion losses are around 8.83 dB and the amount of isolation are around LO/IF 69 dB, LO/RF 30 dB & RF/IF 43 dB. The filters are designed with microstrip line. The transmission lines are synthesized and the designed circuits are through ADS.