Simultaneous estimation of echo path and channel responses usingfull-duplex transmitted training data sequences

To reduce the system initialization time in high-speed full-duplex data transmission over two-wire lines, we propose an efficient full-duplex fast training algorithm which can simultaneously estimate the impulse responses of echo paths and channels at both ends. Two mutually orthogonal periodic sequences are designed and used to co-estimate the near echo, the far echo with bulk delay, and the channel response. The new algorithm can reduce the tap-setting time to half of that required by the traditional half-duplex fast training schemes. The effects of channel noise and symbol rate offset between two ends are examined in terms of both mean-square error (MSE) and signal-to-noise ratio (SNR). Both the theoretical analysis and computer simulation show that there are three degrading factors due to symbol rate offset. The SNR is inversely proportional to the sum of the estimated coefficients, the half period of the training sequences, and the square of symbol rate offset. If the far-signal-to-channel-noise ratio is 30 dB, then the degradation is significant when the symbol rate offset is more than 10 ^-4. If it is 40 dB, then the degradation is significant when the symbol rate offset is above 3×10^-5     

A Configurable Enhanced TTRAM Macro for System-Level Power Management Unified Memory

A twin-transistor random access memory (TTRAM) can provide high speed, low power and high density with CMOS compatible SOI process. However it is difficult to handle as the unified memory required for advanced SoC because it needs the simple control sensing operation for memory compiler, higher cell efficiency, and lower voltage operation for dynamic frequency and voltage control. Enhanced TTRAM (ET²RAM) applies the actively body-bias control technique to realize the low voltage array operation, and never require the negative voltage source. The ET2RAM can realize both 263 MHz at 0.8 V and 10.2 mW at 0.5 V random-cycle operation, higher cell efficiency, and process scalability. It also provides the simple control method suitable for the unified macro for system-level power management SoC with keeping the merits of TTRAM as CMOS compatibility     

Stacking number dependence of size distribution of vertically stacked InAs/GaAs quantum dots

Vertically stacked layer structure is useful for controlling the size distribution of quantum dots. The dependence of the size distribution of quantum dots on the stacking numbers is theoretically and experimentally investigated. We show that the size distribution of quantum dots decreases with increasing the stacking number, and it occurs drastically when the stacking number is changed from 1 to 2. The quantitative analysis on in-plane strain energy distribution is also performed for the explanation.     

A single-power-supply 10-b video BiCMOS sample-and-hold IC

A +5-V single-power-supply 10-b video BiCMOS sample-and-hold IC is described. Video speed, low power, and 10-b accuracy sample-and-hold operation have been achieved using a complementary connected buffer format sample switch. A high-speed p-n-p transistor used in the sample switch is formed by a combination of n-p-n and PMOS transistors. The sample-and-hold operation is accomplished by feeding back the hold capacitor voltage to the sample switch inputs, so that the inputs transfer symmetrically for the hold capacitor voltage at any input level. The sample-and-hold IC has been implemented in 1.2-μm BiCMOS technology and evaluated. The following results have been obtained: 185-MHz 3-dB bandwidth at 22-pF hold capacitor, 63-dB signal-to-noise ratio at 8-MHz full-scale input, 20-ns acquisition time at 1-V step input, 15-ns switch setting time, and 0.1% linearity error. Power dissipation is 150 mW     

Calcite Prisms from Mollusk Shells (Atrina Rigida): Swiss‐cheese‐like Organic–Inorganic Single‐crystal Composites

Biogenic single‐crystal composites, such as sea urchin spines and calcitic prisms from mollusk shells, contain organic macromolecules inside of inorganic single‐crystal matrices. The nanoscale internal structure of these materials, however, is poorly understood, especially how the biomacromolecules are distributed within the crystals without significantly disrupting the crystalline lattice. Here, annular dark‐field scanning transmission electron microscopy and electron tomography reveal, in three dimensions, how biomacromolecules are distributed within the calcitic prisms from Atrina rigida shells. Disk‐like nanopatches, whose scattering intensity is consistent with organic inclusions, are observed to be anisotropically arranged within a continuous, single‐crystalline calcite matrix. These nanopatches are preferentially aligned with the (000l) planes of calcite. Along the crystallographic c‐axis, there are alternating organic‐rich and ‐poor regions on a length scale of tens of nanometers, while, in the ab plane, the distribution of nanopatches is more random and uniform. The structural features elucidated in this work have relevance to understanding the structure–property relationships and formation mechanisms of biominerals, as well as to the development of bio‐inspired strategies to extrinsically tune the properties of single‐crystals.     

Mutual injection-locking properties of monolithically-integratedsurface-emitting multiple-quantum-well distributed feedback lasers

The mutual injection-locking properties of a coupled pair of multiple-quantum-well distributed-feedback lasers with grating output couplers were investigated experimentally and theoretically. When the mutual injection locking occurred, the output of one laser decreased while that of the other increased. The locking curve was asymmetric, and a stable and an unstable locking region existed. From the theoretical analysis, it was found that the phase delay with which the electric field emitted from each laser to the other laser significantly influences the locking characteristics. The increase and decrease of the locked output power are caused by the phase delay. It is also shown that the laser which receives the larger optical injection behaves like a slave laser and the laser which has less optical injection behaves like a master laser, and the shape of the locking curve is determined by the balance between the α parameter and the thermal resistance     

交联剂对PDLC膜电-光性能的影响

在PDLC薄膜中,聚合物网络网孔的大小直接影响着PDLC薄膜的电-光性能。该实验选用光可聚合单体/交联剂/液晶复合材料,经紫外光照射制备PDLC薄膜,研究了交联剂对PDLC薄膜电-光性能的影响。在混合物体系中引入长柔性链的PEGDA1000和短分子链的BDDA,影响了聚合物网络的微观形貌。交联剂分子链的长短对聚合物网络网孔的大小有明显的影响,进而影响了PDLC膜的电-光性能。     

Experimental and numerical analysis of channel-length-dependent electrical properties in bottom-gate,bottom-contact organic thin-film transistors with Schottky contact

Channel length dependence of field-effect mobility and source/drain parasitic resistance in pentacene thin-film transistors with a bottom-gate, bottom-contact configuration was investigated. Schottky barrier effect such as nonlinear behaviors in transistor output characteristics appeared and became more prominent for shorter channel length less than 10 μm, raising some concerns for a simple utilization of conventional parameter extraction methods. Therefore the gate-voltage-dependent hole mobility and the source/drain parasitic resistance in the pentacene transistors were evaluated with the aid of device simulation accounting for Schottky contact with a thermionic field emission model. The hole mobility in the channel region shows smaller values with shorter channel length even after removing the influence of Schottky barrier, suggesting that some disordered semiconductor layers with low carrier mobility exist near the contact electrode. This experimental data analysis with the simulation enables us to discuss and understand in detail the operation mechanism of bottom-gate, bottom-contact transistors by considering properly each process of charge carrier injection, carrier flow near the contact region, and actual channel transport.     

Bias-temperature life tests for planar-type VPE-grown InGaAs/InP heterostructure APD's

The fabrication processings and the preliminary bias-temperature life tests for planar-type InGaAs/InP heterostructure avalanche photodiodes (HAPD's) made from VPE-grown wafers are presented. The plasma deposited SiNxpassivation film showed a surface state density Nssof less than 10¹²cm^-2. eV^-1. An anomalous behavior of Cd diffusion velocity was observed in the process of the guard-ring formation. A Cr/Au p-side electrode made it possible to reduce the contact failure compared to an Au/Zn contact. Bias-temperature life tests were carried out at three temperature levels: 80, 120, and 180°C. Low-bias life tests (V_{R} = 10V) were tried at first for the diodes without a guard-ring structure for times exceeding 10 000 h. The HAPD's with the guard-ring have been tested under the condition of high electric field (>4 times 10^{5}V/cm). The stable devices have been operating up to 6000 h under the high field condition even at 180°C. The HAPD's are still at the prototype stage. Thus, the test results are considered to be encouraging as to achieving highly reliable photodiodes.     

Time division multiplexed OTDR system

A new technique to increase the effective sampling rate of an optical time-domain reflectometer using a time division multiplexing digital sampling averaging procedure is proposed. This permits an increase in distance measuring accuracy of an optical time-domain reflectometer.