RF characteristics of 0.13-μm NMOS transistors for millimeter-wave application

Abstract

Purpose – The purpose of this paper is to present the high-frequency performance of 0.13-μm n-type metal-oxide-semiconductor (NMOS) transistors with various multi-finger configurations for implementation in millimeter-wave (mm-wave) frequency. Design/methodology/approach – A folded-like double-gate transistor layout is designed to enable the transistor to work in the mm-wave region. Different sizes of transistors with variation in finger width (WF ) and number of fingers (NF ) were fabricated to determine the optimum size of the transistor. The extrinsic parasitic elements of selected transistors were extracted and investigated. The radio frequency (RF) performance of these samples were then analyzed and compared. Findings – The proposed layout performed well with the highest maximum oscillation frequency (fmax ) achieved at 122 GHz. Based on the comparison done, the optimum WF obtained for the layout is at 2.0 μm. It is found that the extrinsic parasitic capacitance is more dominant than the parasitic resistance in affecting the fmax . In s-parameter analysis, it is observed that the transistor with the least NF has smaller variance in small-signal gain throughout the measurement frequency. The maximum stable gain for the samples is also found to be roughly similar and independent of NF . Originality/value – A new layout structure for an NMOS transistor that works in mm-wave frequency is proposed. Experimental analyses presented here cover for both NF and WF , unlike others which focus on either NF or WF only.