A double-shunt branch switch structure based on the filter optimization method is introduced to lower the insertion loss.Each branch consists of a series quarter-wavelength impedance converter and a shunt switch device.A distributed Single-Pole Double-Throw (SPDT) switch MMIC treated as a filter issue with this optimization method is implemented in a 0.15 μm GaAs pHEMT technology for the millimeter-wave applications.The chip size of the presented switch is 2.1 mm×1.1 mm.Measurement results show that the SPDT switch exhibits less than 1.3 dB of insertion loss, greater than 23dB of isolation and better than 10 dB of input and output return loss in the frequency range from 23 to 30 GHz.