This paper presents a novel 8T SRAM cell which contains two tail transistors in the pull-down path of the respective inverter to minimize the write power consumption. The simulated results show that the proposed cell consumes about 57.87% lower power and gives faster response compared to the conventional 6T SRAM cell during a write operation. To compensate the read delay and static noise margin (SNM) losses due to the two extra tail transistors in the proposed cell, we have to enlarge the width of these two tail transistors.
We have developed a novel configuration of an X-ray grating interferometer for the phase imaging of a packaged IC chip. A square source grating is used, and a beam splitter and an analyzer grating are positioned downstream of the investigated sample. In the proposed method, the period of source grating is smaller than the last of two gratings, the configuration of which could be implemented for phase imaging. Phase images retrieved using the principle of in-line phase contrast imaging and phase detection are the phase stepping method used in the X-ray grating interferometer. The wrapped phase images of the packaged IC chip are obtained from nine Moiré fringe patterns, using an exposure time of 34ms for each scan.
We investigated the properties of pulse propagation on nonlinear traveling-wave field effect transistors (TW-FET) to develop a method for amplifying short electrical pulses. TW-FETs are a special type of FET whose electrodes are employed not only as electrical contacts but also as transmission lines. Due to the presence of electromagnetic couplings between the gate and drain lines, two different propagation modes called the c mode and π mode are developed on a TW-FET. Moreover, the Schottky contact beneath the gate electrode creates an ideal source of nonlinearity for soliton-like propagation. We can design the TW-FET to amplify only soliton-like pulses carried by one of the two modes and attenuate the ones carried by the other mode. This paper discusses the fundamental properties of a nonlinear TW-FET, including the width and velocity of a soliton-like pulse carried by c and π modes, and gives design criteria of amplification of soliton-like pulses.
Coherent detection can improve the receiver sensitivity and spectral density, so it has become a key technology in realizing the advanced access network. Adding optical heterodyne detection to the wavelength division multiplexing passive optical network (WDM-PON) makes it possible to increase the number of accommodated optical network units (ONUs) and the transmission distance. In this letter, we propose and demonstrate a heterodyne detection scheme that realizes polarization diversity with one photo detector and one receiving circuit by centralizing diversity devices at the transmitter. We experimentally achieved the cost-effective polarization diversity technique which receiver sensitivity fluctuation was 1.2dB, and the power penalty was less than 0.8dB after transmission through 10km single-mode fiber.
A 10-Gb/s trans-impedance amplifier (TIA) with insensitive characteristics to photodiode junction capacitance is demonstrated in 0.13-µm CMOS technology. The TIA has LC-ladder input configuration which allows large bandwidth even with large photodiode capacitance (CPD). In addition, the circuit bandwidth is enhanced with capacitive degeneration and shunt peaking techniques. With CPD of 1.5-pF, our TIA has about two times larger bandwidth compared with conventional TIAs.
A novel modified printed monopole antenna with variable frequency band-notch characteristic for ultra-wideband (UWB) applications is presented. The proposed antenna consists of a truncated ground plane and a radiating patch with two tapered steps. To generate a notch band at 5-6GHz with good level of band-notch a new T-shaped parasitic element placed on the back layer of the substrate along with a simple circular slot etched on the patch is implemented. The proposed antenna has a compact size of 14 × 20mm2, a measured impedance bandwidth of 3.05 to 14.7GHz for VSWR < 2 and exhibits an omni-directional H-plane radiation pattern throughout the UWB frequency range.
This research proposes a new planar hexaband antenna for compact wireless USB dongles. A folded meander-patch and a monopole element are employed to generate multiple broadband resonances supporting WiBro, WLAN, Bluetooth, 2.5/3.5GHz WiMAX, and S-DMB bands. This novel hexaband antenna, built into a compact USB dongle, measures only 10×50×1mm3. The measured 10dB return loss bandwidths of the fabricated antenna are 21.1% (2.29-2.83GHz), 11.6% (3.25-3.65GHz), and 20.2% (5.13-6.28GHz). The radiation efficiency and gain of the antenna are also tested in this study.
In this paper, we propose a method to avoid distributed reservation protocol (DRP) conflicts in WiMedia MAC. A WiMedia device with our method immediately compares its own medium access slots (MASs) to neighbor's requests. If there is a reservation conflict, the device's reservation is modified and a beacon frame based on the modified reservation is transmitted to remove the 65ms delay that occurs when a reservation conflict arises. The simulation result using VBR video traffic indicates that our method reduces reservation conflicts by about 12%. The proposed method is adapted to implement the WiMedia MAC-PHY modem chip.