Browsing by Author "Tsai, Yi-Hsiu"

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A Broadband and Scalable Lossy Substrate Model for RF Noise Simulation and Analysis in Nanoscale MOSFETs With Various Pad Structures
(2009-02-01)
Guo, Jyh-Chyurn
;
Tsai, Yi-Hsiu
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An enhanced lossy substrate model is developed with important features of broadband accuracy and scalability. The broadband accuracy is justified by a good match with open pad S-parameters measured up to 110 GHz and MOSFETs' S- and Y-parameters over 40 GHz. The proven model can accurately simulate four noise parameters (NF(min), R(n), Re(Y(opt)), and Im(Y(opt))) and power spectral density of current noises (S(id) and S(ig)). The scalability has been validated over nanoscale MOSFETs with different finger numbers and adopting various pad structures (lossy, normal, and small pads). This scalable lossy substrate model attributed to two substrate RLC networks under the pads and transmission lines (TMLs) can consistently predict the abnormally strong finger number dependence and nonlinear frequency dependence of noise figure (NF(min)) revealed in devices with lossy pads. The enhanced model is useful in guiding pad and TML layouts for effective reduction of extrinsic noises and low noise design. Using a normal pad structure, the NF(min) can be effectively suppressed to approach the intrinsic performance, which is nearly independent of finger numbers.
RF Noise Shielding Method and Modelling for Nanoscale MOSFET
(2008)
Guo, Jyh-Chyurn
;
Lin, Yi-Min
;
Tsai, Yi-Hsiu
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
RF noise shielding methods with different coverage areas (Pad and TML shielding) were implemented in two port test structures adopting 100-nm MOSFETs. Noise measurement reveals an effective suppression of NF(min) but increase of NF(50), simultaneously from the shielding methods. The suppression of NF(min) is contributed from the reduction of Re(Y(opt)) while the noise resistance R(n) is kept nearly the same. A lossy substrate model developed in our original work for a standard structure without shielding can be easily extended based on the layout and topology of the shielding schemes to predict the noise shielding effect and explain the mechanisms. The extended lossy substrate model indicates that the elimination of substrate loss represented by substrate RLC networks is the major mechanism contributing the reduction of NF(min). However, the increase of parasitic capacitance generated from the shielding structures is responsible for the degradation of f(T) and NF(50). The results provide an important insight and guideline for low noise RF circuit design.