A linearized 2.3GHz CMOS power amplifier with AM-AM and AM-PM distortion correction is presented. The varactors are used at the driver amplifier load to correct the phase distortion and gate bias control of the PA to compensate the amplitude distortion. The proposed CMOS PA has been implemented in 0.13µm CMOS technology. The measured results show that P1dB is increased 1.6dB and PAE is improved from 5.5% to 9% at the condition of -28dB EVM, respectively.
Multispectral imaging has been widely used for high-fidelity color reproduction. For accurate color reproduction, a robust characterization process is essential. In this paper, we present a robust and convenient characterization method for a multispectral imaging system using the irradiance of the illuminant. We measure the irradiance of the illuminant instead of the reference of the color chart, thereby reduces tedious measuring tasks. Furthermore, our method can obtain the spectral reflectance of a scene, which enables realistic relighting and image composition under different illumination conditions. The experiment results demonstrate that our method outperforms the previous method by giving smaller errors in terms of the estimated spectral reflectance, and showing more realistic image composition.
We have proposed and demonstrated an embedded thin film thermoelectric cooler attached between die chip and metal plate for Chip-on-Board (COB) direct assembly. The proposed structure of COB cooler was modeled by electrical equivalent circuit for SPICE simulation including operational heat generation of chip and PWM control of input power supply. The optimum input power of the TEC to achieve maximum temperature difference between chip and heat sink was simulated by using the proposed equivalent circuit. The measured and simulated results offer the possibility of thin film active cooling for COB direct assembly.
We propose an effective compressed memory system to address bandwidth problem of depth data for low-power 3D rendering processors. The proposed memory system performs on-the-fly compression for depth data to be stored into external memory. If the compression rate meets or exceeds a selected threshold value, then the compressed depth data are stored into internal SRAM; otherwise the original depth data are stored into external DRAM. Experimental simulation results show that the proposed memory system could reduces the external DRAM usage by about 82%.
A simple microstrip line fed antenna with thin substrate is proposed in this letter for multi-band wireless applications. The multi-band characteristic was achieved by overlapping an annular slot antenna with two concentric fan shaped patches. The antenna demonstrates three wide impedance bandwidths (VSWR ≤ 2) of 36.3, 63.4 and 25.5% with stable polarization and radiation characteristics.
We propose a customized forwarding (CF) scheme for tree-based application layer multicasts to support real-time interactive multimedia services. We show that CF reduces residual loss rate and play pause frequency significantly.
More and more TVoIP services are emerging on the market using RTP to compensate for the dynamic routing. Interactive applications, however, still suffer from the network's long latency. Offloading to the access network offers a solution. In this paper we present an optimized hardware architecture for a proxy handling RTP packets delivering an acceleration ratio of over 440. The architecture has built-in support for Video-on-Demand, Time-Shifted TV and Fast Channel Change services, and has been successfully tested on a custom FPGA board.
This paper presents a slotted circular waveguide as an open-circuited standard structure. This device as well as its previous stages are simulated with a 3D FDTD program. The dimensions are based on estimations of the MM8048B1® open-circuited standard. The results obtained through a variational method and a static MoM simulation, when compared with those obtained by means of 3D FDTD simulation, are found to be in good agreement, especially in the L-band.
We successfully realized a 1.5µm optical frequency-tunable Cs atomic clock by employing a mode-hop-free 9.19GHz mode-locked erbium fiber laser with an optical etalon in the cavity. We achieved independent control of the optical frequency and the repetition rate (microwave frequency) of the 9.19GHz optical pulse, in which the microwave frequency was controlled without disturbing the optical frequency. The optical frequency was continuously tuned over 1GHz without changing the repetition rate, indicating the possibility of the absolute frequency stabilization of the Cs optical atomic clock.