Dual-Band Single-Output WLAN Directional Coupler in a SOI CMOS Process

A new dual-band directional coupler for wireless local area network (WLAN) is proposed to achieve high directivity. Single coupling line couples both 2.4-2.5 GHz and 4.9-5.85 GHz signals. The coupler has been implemented in the SOI CMOS process with an electrostatic static discharge (ESD) protection device. The measurement results showed 0.15 dB insertion loss and 23 dB directivity at 2.4-2.5 GHz, and 0.42 dB and 28 dB at 4.9-5.85 GHz, respectively. Its human body model (HBM) ESD robustness is higher than 4 kV without DC power consumption.