A power divider/combiner circuit, which simultaneously achieves wide bandwidth, flat gain characteristics, and bidirectional operation, is proposed for multichannel broadband system applications. The proposed circuit utilizes cascode-based bidirectional amplifier cores, which steer the operation modes between a divider and a combiner depending on the control input, and a two-stage distributed-amplifier topology with artificial transmission lines. Implemented in a 130-nm silicon-germanium BiCMOS technology platform, the proposed divider/combiner provides the advantage of seamless integration with digital control blocks. The power divider/combiner exhibits the flat in-band gain of 9 dB and the operational bandwidth of 2-22 GHz, which covers S-, C-, X-, and Ku-bands. In addition, it shows the amplitude imbalance of 0.8 dB, the phase imbalance of 3.5 degrees, the port-to-port isolation of 22 dB, the output 1-dB compression point of 3 dBm, and good impedance matching under 100-mW dc power consumption.