| Summary: | 碩士 === 國立清華大學 === 電子工程研究所 === 96 === With the growing popularity of portable wireless units, the consumer and electronic industry demand for high performance, high integration, and low cost transistors. The RF devices and integrated circuits were dominated by III-V based technologies owning to their high-speed characteristics. Recently, CMOS technology keeps improving and the cut-off frequency (f T) and maximum oscillation frequency (fmax) have both reached above 100 GHz. These advanced transistors have made it possible for using CMOS technology for microwave applications.
In this study, we focused on layout design of 65-nm n-MOSFETs for improved high-frequency device characteristics. By changing the inner wire, the parasitic gate-source capacitance Cgs and gate-drain capacitances Cgd can be reduced significantly. The parasitic source resistance also becomes smaller in the proposed design. Compared with the conventional multi-finger design provided by foundry, the devices with optimized gate finger layout (Device II) present ~15 % and ~19 % improvement on f T and fmax. With the further optimized parasitic resistances by using less metal layer (Device III), the f T and fmax shows ~21 % and ~22 % enhancement. For quantitatively investigation, the Cgd and Cgs are extracted from S-parameters. The measured results indicate the Cgd and Cgs reduced up to ~23 % and ~11 % in the latter case. The flicker noise modeling is also investigated for the devices. The noise variation and current calibration technique are incorporated for a more accurate flicker noise model.
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