Ka-Band CMOS Absorptive SP4T Switch With One-Third Miniaturization

An Ka-band absorptive single-pole four-throw (SP4T) switch in 28-nm CMOS process is presented. By capacitive matching and loading method, only four λ/6 transmission lines (t-line) are used for the proposed switch without additional series switches. The length of the t-line used in the proposed switch is only 1/3 of that of the quarter-wave t-line based absorptive switch. To improve switch performance, low threshold-voltage transistors and source and drain of transistors are biased for power handling capability. The measured insertion loss and isolation are 3.5 dB and 20 dB at 28 GHz. Return losses of on-state and off-state ports are less than -10 dB and -16 dB from 26 GHz to 33 GHz. The measured input 1-dB compression point is more than 15 dBm. The chip area is 0.53 mm
²
and electrical size is 0.0047×(λ
_g
)
²
excluding pads and internal matching circuits that is the smallest electrical size among the millimeter-wave CMOS absorptive SP4T switches.