1,084 research outputs found
A New Transmitted Reference Pulse Cluster Based Ultra-Wideband Transmitter Design
An energy efficient ultra-wideband (UWB) transmitter based on the novel
transmitted reference pulse cluster (TRPC) modulation scheme is presented. The
TRPC-UWB transmitter integrates, namely, wideband active baluns, wideband I-Q
modulator based up-conversion mixer, and differential to single-ended
converter. The integrated circuits of TRPC-UWB front end is designed and
implemented in the 130-nm CMOS process technology. the measured worst-case
carrier leakage suppression is 22.4 dBc, while the single sideband suppression
is higher than 31.6 dBc, operating at the frequency from 3.1 GHz to 8.2 GHz.
With adjustable data rate of 10 to 300 Mbps, the transmitter achieves a high
energy efficiency of 38.4 pJ/pulse.Comment: 4 page, 8 figure
Broadband Quantum Efficiency Enhancement in High Index Nanowires Resonators
Light trapping in sub-wavelength semiconductor nanowires (NWs) offers a
promising approach to simultaneously reducing material consumption and
enhancing photovoltaic performance. Nevertheless, the absorption efficiency of
a NW, defined by the ratio of optical absorption cross section to the NW
diameter, lingers around 1 in existing NW photonic devices, and the absorption
enhancement suffers from a narrow spectral width. Here, we show that the
absorption efficiency can be significantly improved in NWs with higher
refractive indices, by an experimental observation of up to 350% external
quantum efficiency (EQE) in lead sulfide (PbS) NW resonators, a 3-fold increase
compared to Si NWs. Furthermore, broadband absorption enhancement is achieved
in single tapered NWs, where light of various wavelengths is absorbed at
segments with different diameters analogous to a tandem solar cell. Overall,
the single NW Schottky junction solar cells benefit from optical resonance,
near bandgap open circuit voltage, and long minority carrier diffusion length,
demonstrating power conversion efficiency (PCE) comparable to single Si NW
coaxial p-n junction cells11, but with much simpler fabrication processes
Stable closed characteristics on partially symmetric convex hypersurfaces
AbstractLet n be a positive integer and P=diag(−In−κ,Iκ,−In−κ,Iκ) for some integer κ∈[0,n]. In this paper, we prove that for any convex compact smooth hypersurface Σ in R2n with n⩾2 there always exists at least one closed characteristic on Σ which possesses at least 2n−4κ Floquet multipliers on the unit circle of the complex plane, provided Σ is P-symmetric, i.e., x∈Σ implies Px∈Σ
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