A New mm-Wave Multiple-Band Single-Pole Multiple-Throw Switch with Variable Transmission Lines

This article a new multiple-band single-pole N-throw (SPNT) switch topology suitable for mm-wave applications. Compared to a conventional shunt-type SPNT switch, the proposed SPNT operates in the multiple frequency bands by adopting a variable transmission-line (T-line) structure. The variable T-line (VTL) structure consists of multiple sections of T-line and multiple shunt switches. Therefore, it realizes a variable quarter-wave line at different frequencies depending on the ON-OFF configuration of the multiple shunt switches. To validate the proposed topology, two versions of a triple-band SP3T switch operating at 20, 30, and 40 GHz are demonstrated in a 65-nm bulk CMOS technology. The first version (SW1) employs a minimum number of shunt switches in the VTL structure, thus minimizing the insertion loss. The second version (SW2) includes extra shunt switches in the VTL, thus improving the isolation. The measurement shows that SW1 exhibits insertion loss of 3, 3.4, and 3.6 dB at 20, 30, and 40 GHz, respectively. The isolations are 22.8 or 20 dB at 20 GHz, 18.5 or 21.5 dB at 30 GHz, and 19.7 or 23.5 dB at 40 GHz, depending on the operation mode. On the other hand, SW2 shows improved isolation of 36.2 or 45 dB at 20 GHz, 19.6 or 42.8 dB at 30 GHz, and 22.7 or 38.6 dB at 40 GHz. The insertion losses are 3.6, 3.8, and 3.9 dB at 20, 30, and 40 GHz, respectively.