Browsing by Author "Lee, Po-Yi"

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Analytical Noise Optimization of Single-/Dual-Band MOS LNAs With Substrate and Metal Loss Effects of Inductors
(2019-07-01)
Chang, Wei Ling
;
Meng, Chinchun
;
Ni, Jung-Hung
;
Ch, Kai-Chun
;
Chang, Chih-Kai
Analytical noise formulations and design optimization of single- and dual-band inductively source-degenerated MOS low-noise amplifiers (LNAs) with the substrate and metal loss effects of on-chip inductors are established in this paper. It reveals that the noise figures of both single-/dual-band LNAs degrade substantially under the consideration of the loss effects. However, by increasing the device size, the noise optimization methodology of simultaneous noise and input match for a single-band LNA still holds true with concern for the loss effects. For a dual-band LNA, analytical noise optimization for a balanced noise design is established for inductors with metal and substrate loss and indicates a larger device size. The substrate and metal loss effects of inductors can be mitigated using integrated passive device (IPD) process for the input match network. The demonstrated single-band 0.18-mu m MOS LNAs with and without IPD process show noise figures of 1.53 and 2.52 dB at 2.4 GHz, respectively. Subsequently, the implemented dual-band 0.18-mu m MOS LNAs with and without IPD process show noise figures of 1.6/2.6 and 3.25/4.1 dB at 2.4/5 GHz, respectively.
Design of photonic directional couplers as phase selectors
(2013-06-01)
Lee, Po-Yi
;
Huang, Chih-Hsien
;
Hsieh, Wen-Feng
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光電工程學系
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Department of Photonics
A phase selector is designed by relatively sliding two coupled identical photonic crystal waveguides (PCWs) of a photonic directional coupler (DC). By solving the coupled equations analytically derived from the tight-binding theory, symmetry breaking in the crossing of dispersion curves can be observed as countersliding two degenerated waveguides along the propagation direction. There exists a different phase shift between two eigenmodes by varying the sliding distance and the operating frequency. Numerical simulations of DCs made of photonic crystal slabs were used to verify the correctness of our theoretical predictions and to discuss thoroughly the underlying physics of the symmetry-breaking system. The design concept is provided for a phase selector or a beam splitter whose output phase difference can be controlled by the sliding distance of two PCWs. (C) 2013 Optical Society of America
The properties and design concepts of photonic directional couplers made of photonic crystal slabs
(2010-11-24)
Huang, Chih-Hsien
;
Wu, Jing-Nuo
;
Lee, Po-Yi
;
Hsieh, Wen-Feng
;
Cheng, Szu-Cheng
The properties and design concepts of air-defect symmetric and asymmetric directional couplers (DCs) made of photonic crystal slabs (PCSs) are investigated by the tight-binding theory. We give criteria in both cases for determining the specific frequency, named as the decoupling point, at which the even (-like) and odd (-like) parities of eigenmodes should switch. Two dispersion curves will cross in symmetric DCs but not in asymmetric DCs because eigenfrequencies of isolated photonic waveguides (PCWs) are different in asymmetric DCs. In the dielectric-rod PCS, the decoupling point of the DC is located almost at the same wave vector as a two-dimensional (2D) DC with only a blue shift in its frequency. Therefore, 2D simulation can give a primary result in designing a dielectric-rod DC. On reducing the radius of the defect rods, the increase in coupling coefficients leads to a faster group velocity and a longer coupling length. On the other hand, the dispersion curves of the air-hole PCS DC are no longer parallel to those of the 2D DC so that performing a 3D simulation is necessary in designing an air-hole PCS DC with enlarged air holes. Moreover, the dispersion curve of the single PCW is no longer located at the centre of the curves of the symmetric DC and the group velocity may become negative which is not observed in the dielectric-rod PCS. The simulation results indicate that the coupling length of an air-defect DC can be achieved as short as 5 lattice constants, which is much smaller than that made of dielectric defects in air-hole PCS DCs.