A wideband SPDT switch in standard bulk 0.13-μm CMOS process is demonstrated in this paper. In order to extend the operation frequency, the traveling-wave circuit topology is utilized. Due to the different requirements in the transmit and receive paths, the switch is designed to be asymmetric. In the receive path, the switch achieves a measured insertion loss less than 2.7 dB, a measured isolation better than 26 dB from 27 to 50 GHz. On the other hand, for the transmit path, the switch also achieves a measured insertion loss less than 4.4 dB, and an isolation better than 14 dB from 30 to 63 GHz. At 40 GHz, a measured input P
of 13.8 dBm is attained. The chip size is only 0.8 × 0.5 mm
. The measured data agree with the simulation results well. To our knowledge, this work is the first CMOS switch in millimeter-wave frequency range.