A high performance PIN diode single-pole-single-throw (SPST) switch for W-band application using a low cost approach was developed. By utilizing flip-chip PIN diodes mounted onto a separately fabricated passive circuit having a quartz substrate, a W-band quasi-monolithic millimeter-wave integrated circuit (Q-MMIC) switch was achieved. A 3-D PIN diode model and a compensation structure were adopted to acquire a low loss and high isolation switch. The measurement results show the minimum insertion loss is about 0.5 dB at 88 GHz and less than 2 dB over the frequency range of 80 to 101 GHz. The isolation is greater than 30 dB from 84 to 105 GHz. The total size of the switch is 1.5 mm× 3.0 mm.quasi-monolithic millimeter-wave integrated circuit（Q-MMIC）,