Wide band on-chip slot antenna with back-side etched trench for W-band sensing applications

This paper presents the design and characterization of a highly integrated, wideband on-chip radiometer, composed of a slot antenna, RF-MEMS Dicke Switch, LNA and a wideband power detector. The highly integrated single-chip RF front-end is dedicated for broadband sensing up to 110 GHz. Both antenna and radiometer are fabricated in a 0.25 μm SiGe BiCMOS process. The antenna design takes benefit of the back-side etched trench, offered by the technology. This is used to reduce losses due to the presence of the low resistivity silicon substrate. Additionally, the trench is specially shaped, as to improve the wideband matching of the antenna. The on-chip slot antenna design covers a wide bandwidth (70-110 GHz) with 0 dBi gain and 64% efficiency, both simulated at 94 GHz. The measured bandwidth spans 85 to 105 GHz. The W-band SiGe detector circuit has close to 20 GHz of operational bandwidth (S₁₁≤-10 dB at 75-92 GHz) and presents a responsivity of 3-5kV/W (NEP=10-16 pW/Hz^½) at 83-94 GHz.