Modified CMOS monolithic stacked coupled stripline balun for millimeter-wave applications

In this paper, a modified CMOS monolithic stacked coupled stripline balun for millimeter-wave applications is proposed. Implemented in TSMC's one-poly eight-metal (1P8M) 0.13 μm mixed-signal (MS)/RF CMOS process, it exhibits a good performance from 28.6 to 35.3 GHz. The minimum insertion loss is only about 0.83 dB. The symmetry is good. The absolute magnitude imbalance is <;0.6 dB and absolute phase imbalance is <;10° within the hole 1-dB bandwidth frequency range. The return loss is <;-10 dB from 28.6 to 35.3 GHz.