In order to address the issue of 220 GHz receiver protection, a single-pole single-throw (SPST) switch based on GaAs PIN diodes is introduced in this research. The PIN diode with an I layer thickness of 400 nm and a cut-off frequency over 1.5THz was created in order to enable the SPST switch to operate in the terahertz frequency range. Therefore, a 220 GHz quasi-MMIC SPST switch was designed using GaAs PIN diodes and a 50 μm thin-film quartz foundry. The measurement reveals that the isolation is > 29 dB, insertion loss is < 3.2 dB in the frequency range of 220 GHz to 230 GHz and IP1dB is 17 dBm at 220 GHz.