K-band balun with slot pattern ground for wide operation using 0.18 /spl mu/m CMOS technology

A K-band balun with a slot pattern ground, which is based on the Marchand type, is proposed using the TSMC 0.18 µm CMOS process. The slot pattern ground is applied to the balun to achieve wide bandwidth. This type of balun provides wide bandwidth of 54.5% for amplitude difference less than 1 dB and phase difference less than 5° (18.4–32.2 GHz). Also, it satisfies 10 dB return loss and 5 dB insertion loss in the operating frequency.