Micromachined CMOS E‐band bandpass coplanar filters

Abstract

AbstractIn this work, E‐band CMOS coplanar filters, whose initial design is made according to quasi‐ TEM‐approximation‐based analytical models, are implemented. To study the substrate effects, the CMOS‐compatible inductively coupled‐plasma (ICP) deep trench technology is used to selectively remove the silicon underneath the filter completely. For the filter with top metal thickness of 0.93 μm after the backside ICP etching, the results show that the input matching bandwidth, i.e. S11 below −10 dB, moves from lower 39.8–81.4 GHz‐band to higher 55.9–94.1 GHz‐band, and the 3‐dB bandwidth of S21 moves from lower 43.5–76.3 GHz‐band to higher 54.5–93.3 GHz‐band. In addition, a 4.67 dB improvement [from −8.86 dB (at 58.5 GHz) to −4.19 dB (at 74.5 GHz)] in peak S21 was achieved. These results show that for the design of passive coplanar devices in the E‐band, the quasi‐TEM‐ approximation‐based analytical models can be used and the backside ICP etching is effective to reduce the substrate loss and parasitic capacitance. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3123–3125, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23873