A 40-50-GHz SiGe 1 : 8 differential power divider using shielded broadside-coupled striplines

This paper presents a 1 : 8 differential power divider implemented in a commercial SiGe BiCMOS process using fully shielded broadside-coupled striplines integrated vertically in the silicon interconnect stackup. The 1 : 8 power divider is only 1.12 x1.5 mm² including pads, and shows 0.4-dB rms gain imbalance and <3deg rms phase imbalance from 40 to 50 GHz over all eight channels, a measured power gain of 14.9 plusmn0.6 dB versus a passive divider at 45 GHz, and a 3-dB bandwidth from 37 to 52 GHz. A detailed characterization of the shielded broadside-coupled striplines is presented and agrees well with simulations. These compact lines can be used for a variety of applications in SiGe/CMOS millimeter-wave circuits, including differential signal distribution, miniature power dividers, matching networks, filters, couplers, and baluns.