A low-loss compact-size edge-coupled 4-way balun that simultaneously converts a single-ended signal to two pairs of differential signals is proposed. A 2-way combined differential power amplifier (PA) operating at 60 GHz is designed with the proposed 4-way balun in 0.18 µm SiGe technology. It consists of two identical 3-stage differential unit PA cells, which is internally transformer-coupled and capacitive-neutralized. The designed PA achieves a small signal 3-dB bandwidth from 43 to 67 GHz, with a peak gain of 20 dB. The 1 dB power compression point (P1dB) is 21.6 dBm and saturated output power (PSAT) is 22.7 dBm, with power added efficiency of 23.5% at PldB and 27.7% at PSAT. The modulation test shows that the PA can deliver 18.1 / 15.2 dBm average output power with −14.5 / −21.8 dB error-vector magnitude when operating with IEEE 802.11ad modulation coding schemes (MCS) 9 / IEEE 802.11ad MCS 12 signals.