A compact V-band star mixer using compensated overlay capacitors in dual baluns

A compact V-band star monolithic microwave integrated circuit mixer has been designed using compensated overlay capacitors in dual baluns for the input of local oscillator and radio frequency ports. The reduced-size balun can be simply realized by shunting overlay capacitor in either input or end of balun. The proposed V-band star mixer achieved a conversion loss of 8.6 dB, the port-to-port isolations better than 18 dB, and an input 1-dB compression point higher than 7.7 dBm at 60 GHz. Moreover, better than 50% length reduction of dual balun was achieved, and chip size of star mixer including pads was less than 0.68 × 0.59 mm ².