A W-band single-pole double-throw (SPDT) switch based on magnetically coupled overlapped transformers with a single-ended input and two differential outputs is presented. It achieves low loss and high isolation among CMOS switches by means of leakage-canceling cross-coupled capacitors. The overlapped transformer structure comprising edge-coupled and broadside-coupled transformers integrated in the same are a enables realization of a compact balun-embedded SPDT switch. The insertion losses are measured to be 2.67-3.47 dB at frequencies of 75-100 GHz, and the isolation is 14.3-17 dB from75-100 GHz. The switch has a small chip area of 0.013 mm(2) without pads.