Browsing by Author "Cho, Hsiu-Ying"

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A Novel Transmission-Line Deembedding Technique for RF Device Characterization
(2009-12-01)
Cho, Hsiu-Ying
;
Huang, Jiun-Kai
;
Kuo, Chin-Wei
;
Liu, Sally
;
Wu, Chung-Yu
A novel transmission-line deembedding technique is presented in this paper. With this technique, the left- and right-side ground-signal-ground probe pads can be extracted directly using two transmission-line test structures of length L and 2L. An additional through structure is designed using via-stack deembedding, which is unique among current deembedding methods. The advantages of the proposed method include the following: 1) smaller silicon area; 2) discontinuity between the pad and interconnect; 3) substrate coupling and contact effects; and 4) employment of via-stack deembedding. The proposed novel methodology is a great breakthrough in the area of ultrahigh-frequency deembedding and should enable more accurate RF models to be developed. In the proposed methodology, intrinsic slow-wave CPW transmission-line structures are placed on the interlevel metallization layers, as they are the most appropriate RF device for cascade-based deembedding method involving the via-stack deembedding technique. Experimental results have demonstrated that attenuation loss and wavelength can be optimized by changing the metal density and the position of the metal layer on the floating shields. Both measurement and electromagnetic-wave simulations were performed up to 50 GHz. With a shortened wavelength, a reduction in silicon area of more than 66% can be achieved by using optimized slot-type floating shields.
High-Performance Slow-Wave Transmission Lines With Optimized Slot-Type Floating Shields
(2009-08-01)
Cho, Hsiu-Ying
;
Yeh, Tzu-Jin
;
Liu, Sally
;
Wu, Chung-Yu
;
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A novel slow-wave transmission line with optimized slot-type floating shields in advanced CMOS technology is presented. Periodical slot-type floating shields are inserted beneath the transmission line to provide substrate shielding and to shorten the electromagnetic (EM) propagation wavelength. This is the first study that demonstrates how the wavelength, attenuation loss, and characteristic impedance can be adjusted by changing the strip length (SL), strip spacing (SS), and metal layer position of the slot-type floating shields. Wavelength shortening needs to be achieved with a tradeoff between slow-wave effect and attenuation loss. The slot-type floating shields with different SLs, SSs and metal layer positions are analyzed. It is concluded that minimum SL provides the most optimal result. A design guideline can be established to enable circuit designers to reach the most appropriate slot-type floating shields for optimal circuit performance. Transmission line test structures were fabricated by using 45-nm CMOS process technology. Both measurement and EM waves simulation were performed up to 50 GHz. Transmission lines are frequently used at a length of half-or quarter-wavelength. With a shortened wavelength, a saving in silicon area of more than 67% can be achieved by using optimized slot-type floating shields. Experimental results demonstrated a higher effective relative permittivity value, which is improved by a factor of more than 9, and a better quality factor, which is improved by a factor of more than 6, as compared to conventional transmission lines.