A 210 – 270 GHz Compact Power Combiner Using Three-Conductor Sub-Quarter-Wavelength Balun in 130-nm SiGe BiCMOS

This paper presents a compact power combiner/splitter based on three-conductor structure, and it benefits from the sub-quarter-wavelength transmission line, which significantly improves the die area utilization compared to the conventional one. This balun leads to a small area of 0.018 mm
²
. According to the simulated results, the transmission loss of 1-to-4 structure is less than 2 dB in the range of 210 - 270 GHz, and the amplitude/phase imbalance is less than 1 dB / 2° covering G-band, respectively. The embedded impedance transformation flattens the operation band and output impedance of the differential ports can be adjusted to match the optimum impedance of the power amplifier.