Po-Chang Wu

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We focus on investigating the dielectric behaviors and the low-frequency texture transitions in a cholesteric liquid crystal (CLC) doped with graphene nanoplatelets (GNPs) by means of dielectric spectroscopy and measurements of electro-optical responses. The experimental results indicate that incorporating GNPs at a content of 0.5 wt% into the CLC leads to(More)
A high-gain gate-pumped down-conversion mixer at 60 GHz is realized in a standard 90-nm CMOS process. The proposed mixer adopted a Darlington cell and a microstrip-line Lange coupler to yield wide 3-dB bandwidth from 5 to 65 GHz. The measured performance demonstrates a conversion gain (CG) of 6 dB at 4.2-mW power consumption. The maximum CG is 6.5 dB at 36(More)
This paper investigates the spectral properties of a one-dimensional photonic crystal (PC) containing an inhomogeneous polymer- dispersed liquid crystal (PDLC) as a defect layer. Experimental results indicate that the voltage-induced reorientation of LC molecules between the light-scattering and transparent states in the PDLC enables the electrical tuning(More)
The ionic effect in nematic liquid-crystal (LC) cells containing the azo dye methyl red was investigated by means of dielectric spectroscopy, measurements of voltage holding ratio (VHR) and ultraviolet/visible absorption spectroscopy. The experimental results indicated that incorporating a minute amount of the methyl red (< 0.03 wt%) in the LC host leads to(More)
This paper proposes a 2.4 GHz SiGe HBT differential power amplifier (PA) with a novel on-chip variable gain active predistorter (PD) for linearity enhancement. The fully differential active PD provides an open collector adaptive bias control which can effectively enhance the linearity while improve power added efficiency (PAE). The PA with active PD(More)
We propose a memorable and electrically tunable photonic device by infiltrating a dual-mode chiral-doped dual-frequency liquid crystal (LC) as the central defect layer in a one-dimensional photonic crystal (PC). According to the transmission properties of this structure, the wavelength tunability of defect modes is obtained by manipulating the LC layer in(More)
In the past decades, the Internet usage has increased dramatically. For the network security, the network packet filtering is an important strategy to identify malicious network packets. However, malicious attacks spread much faster than network administrators can respond. The software-only implementations of filter are unlikely to meet the performance(More)