An accurate behavioral model of a DAC-embedded opamp (DAC-opamp) is developed for a yield-ensuring LCD column driver design. A lookup table for the V-I curve of the unit differential pair in the DAC-opamp is extracted from a circuit simulation and is later manipulated through a random error insertion. Virtual ground assumption simplifies the output voltage estimation algorithm. The developed behavioral model of a 5-bit DAC-opamp shows good agreement with the circuit level simulation with less than 5% INL difference.

We propose a CMOS circuit that can be used as an equivalent to resistors. This circuit uses a simple differential pair with diode-connected MOSFETs and operates as a high-resistance resistor when driven in the subthreshold region of MOSFETs. Its resistance can be controlled in a range of 1-1000 MΩ by adjusting a tail current for the differential pair. The results of device fabrication with a 0.35-µm 2P-4M CMOS process technology is described. The resistance was 13 MΩ for a tail current of 10 nA and 135 MΩ for 1 nA. The chip area was 105 µm110 µm. Our resistor circuit is useful to construct many high-resistance resistors in a small chip area.

A low power impulse radio ultra-wideband (IR-UWB) receiver for DC-960 MHz band is proposed in this paper. The proposed receiver employs multiple DC power-free charge-domain sampling correlators to eliminate the need for phase synchronization. To alleviate BER degradation due to an increased charge injection in a subtraction operation in the sampling correlator than that of an addition operation, a comparator with variable threshold (=offset) voltage is used, which enables an addition-only operation. The developed receiver fabricated in 1.2 V 65 nm CMOS achieves the lowest energy consumption of 17.6 pJ/bit at 100 Mbps in state-of-the-art correlation-based UWB receivers.

Chinese new words and their part-of-speech (POS) are particularly problematic in Chinese natural language processing. With the fast development of internet and information technology, it is impossible to get a complete system dictionary for Chinese natural language processing, as new words out of the basic system dictionary are always being created. A latent semi-CRF model, which combines the strengths of LDCRF (Latent-Dynamic Conditional Random Field) and semi-CRF, is proposed to detect the new words together with their POS synchronously regardless of the types of the new words from the Chinese text without being pre-segmented. Unlike the original semi-CRF, the LDCRF is applied to generate the candidate entities for training and testing the latent semi-CRF, which accelerates the training speed and decreases the computation cost. The complexity of the latent semi-CRF could be further adjusted by tuning the number of hidden variables in LDCRF and the number of the candidate entities from the Nbest outputs of the LDCRF. A new-words-generating framework is proposed for model training and testing, under which the definitions and distributions of the new words conform to the ones existing in real text. Specific features called "Global Fragment Information" for new word detection and POS tagging are adopted in the model training and testing. The experimental results show that the proposed method is capable of detecting even low frequency new words together with their POS tags. The proposed model is found to be performing competitively with the state-of-the-art models presented.

In this letter, a new CCM material, adding Ni powder to a conventional CCM, for X-band applications is designed and analyzed to improve the SE. To obtain the SE of the fabricated CCM accurately, material constants of the CCM of the permittivity and permeability were extracted using transmission/reflection measurements. Using the material constants derived from the measurement, the SE was calculated and the results were verified using a commercial full-wave three-dimensional electromagnetic wave simulator. The SE of the proposed the CCM was improved by approximately 4 dB in the X band compared to that of a conventional CCM. The CCM proposed in this paper can be applied as a shielding material as well as for housing of various communication systems and electrical instruments.

We propose a gate-all-around tunnel field effect transistor (GAA TFET) having a n-doped layer at the source junction and investigate its electrical characteristics with device simulation. By introducing the n-doped layer, band-to-band tunneling area is increased and tunneling barrier width is decreased. Also, electric field induced by gate bias is increased by the surrounding gate structure, which makes it possible to obtain a more abrupt band-bending. These effects bring about a significant improvement in on-current and subthreshold characteristics. GAA TFET with n-doped layer shows subthreshold swing at Id = 1 nA/µm of 32.5 mV/dec, average subthreshold swing of 20.6 mV/dec. With comparison to other TFET structures, the merits of the proposed device are demonstrated and performance dependences on device parameters are characterized by extensive simulations.

Design of the 30 nm FinFETs and Double Gate MOSFETs with the halo structure for suppressing the threshold voltage roll-off and improving the subthreshold swing at the same time is proposed for the first time. The performances of nano scale FinFETs and Double Gate MOSFETs with the halo structure are analyzed using a two-dimensional device simulator. The device characteristics, focusing especially on the threshold voltage and subthreshold slope, are investigated for the different gate length, body thickness, and halo impurity concentration. From the viewpoint of body potential control, it is made clear on how to design the halo structure to suppress the short channel effects and improve the subthreshold-slope. It is shown that by introducing the halo structure to FinFETs and Double Gate MOSFETs, nano-scale FinFETs and Double Gate MOSFETs achieve an improved S-factor and suppressed threshold voltage Vth roll-off simultaneously.

In this paper, a modified Belief Propagation (BP) decoding algorithm for low-density parity check (LDPC) codes based on minimum mean square error (MMSE) criterion is proposed. This modified algorithm uses linear equation to replace the hyperbolic function in the original BP algorithm and optimizes the linear approximation error based on MMSE criterion. As a result, compared with the standard BP algorithm the computational complexity is reduced significantly as the modified algorithm requires only addition operations to implement. Besides that simulation results show our modified algorithm can achieve an error performance very close to the BP algorithm on the additive white Gaussian noise channel.

This letter presents an approach to the construction of multiple-rate quasi-cyclic (QC) low-density parity-check (LDPC) codes based on hyperplanes (µ-flats) of two different dimensions in Euclidean geometries. The codes constructed with this method have the same code length, multiple-rate and large stopping sets while maintaining the same basic hardware architecture. The code performance is investigated in terms of the bit error rate (BER) and compared with those of the LDPC codes which are proposed in IEEE 802.16e standard. Simulation results show that our codes perform very well and have low error floors over the AWGN channel.

Since the structured quasi-cyclic low-density parity-check (QC-LDPC) codes for most modern wireless communication systems include multiple code rates, various block lengths, and the corresponding different sizes of submatrices in parity check matrix (PCM), the reconfigurable LDPC decoder is desirable and the permutation network is needed to accommodate any input number (IN) and shift number (SN) for cyclic shift. In this paper, we propose a novel permutation network architecture for the reconfigurable QC-LDPC decoders based on Banyan network. We prove that Banyan network has the nonblocking property for cyclic shift when the IN is power of 2, and give the control signal generating algorithm. Through introducing the bypass network, we put forward the nonblocking scheme for any IN and SN. In addition, we present the hardware design of the control signal generator, which can greatly reduce the hardware complexity and latency. The synthesis results using the TSMC 0.18 µm library demonstrate that the proposed permutation network can be implemented with the area of 0.546 mm2 and the frequency of 292 MHz.

A 7 bit 1.0 Gsps Cascaded Folding ADC is presented. This ADC employs cascaded folding architecture with 3-degree folders. A new reset technique and layout shuffling enable the ADC to operate at high-speed with low power consumption. Implemented in a 90 nm CMOS process technology the ADC consumes 230 mW with 1.2 V and 2.5 V supplies and has a SNR of 38 dB.

We have proposed a human-area networking technology that uses the surface of the human body as a data transmission path and uses an AC electric field signal below the resonant frequency of the human body. This technology aims to achieve a "touch and connect" intuitive form of communication by using the electric field signal that propagates along the surface of the human body, while suppressing both the electric field radiating from the human body and mutual interference. To suppress the radiation field, the frequency of the AC signal that excites the transmitter electrode must be lowered, and the sensitivity of the receiver must be raised while reducing transmission power to its minimally required level. We describe how we are developing AC electric field communication technologies to promote the further evolution of a human-area network in support of ubiquitous services, focusing on three main characteristics, enabling-transceiver technique, application-scenario modeling, and communications quality evaluation. Special attention is paid to the relationship between electro-magnetic compatibility evaluation and regulations for extremely low-power radio stations based on Japan's Radio Law.

In order to explore the feasibility of large-scale subthreshold logic circuits and to clarify the lower limit of supply voltage (VDD) for logic circuits, the dependence of the minimum operating voltage (VDD min ) of CMOS logic gates on the number of stages, gate types and gate width is systematically measured with 90 nm CMOS ring oscillators (RO's). The measured average VDD min of inverter RO's increased from 90 mV to 343 mV when the number of RO stages increased from 11 to 1 Mega, which indicates the difficulty of VDD scaling in large-scale subthreshold logic circuits. The dependence of VDD min on the number of stages is calculated using the subthreshold current model with random threshold voltage (VTH) variations and compared with the measured results, and the tendency of the measurement is confirmed. The effect of adaptive body bias control to compensate purely random VTH variation is also investigated. Such compensation would require impractical inverter-by-inverter adaptive body bias control.

In this letter, we learned overcomplete filters to model rich priors of nature images. Our approach extends the Gaussian Scale Mixture Fields of Experts (GSM FOE), which is a fast approximate model based on Fields of Experts (FOE). In these previous image prior model, the overcomplete case is not considered because of the heavy computation. We introduce the assumption of quasi-orthogonality to the GSM FOE, which allows us to learn overcomplete filters of nature images fast and efficiently. Simulations show these obtained overcomplete filters have properties similar with those of Fields of Experts', and denoising experiments also show the superiority of our model.

In this paper, a motion field representation algorithm based on directional edge information has been developed. This work is aiming at building an ego-motion detection system using dedicated VLSI chips developed for real time motion field generation at low powers . Directional edge maps are utilized instead of original gray-scale images to represent local features of an image and to detect the local motion component in a moving image sequence. Motion detection by edge histogram matching has drastically reduced the computational cost of block matching, while achieving a robust performance of the ego-motion detection system under dynamic illumination variation. Two kinds of feature vectors, the global motion vector and the component distribution vectors, are generated from a motion field at two different scales and perspectives. They are jointly utilized in the hierarchical classification scheme employing multiple-clue matching. As a result, the problems of motion ambiguity as well as motion field distortion caused by camera shaking during video capture have been resolved. The performance of the ego-motion detection system was evaluated under various circumstances, and the effectiveness of this work has been verified.

This paper studies scattering and diffraction of a TE plane wave from a periodic surface with semi-infinite extent. By use of a combination of the Wiener-Hopf technique and a perturbation method, a concrete representation of the wavefield is explicitly obtained in terms of a sum of two types of Fourier integrals. It is then found that effects of surface roughness mainly appear on the illuminated side, but weakly on the shadow side. Moreover, ripples on the angular distribution of the first-order scattering in the shadow side are newly found as interference between a cylindrical wave radiated from the edge and an inhomogeneous plane wave supported by the periodic surface.

We propose a novel short-range wireless communications technology that uses quasi-static electric fields; it enables data communication between devices separated by up to 10 cm via dielectric media at a speed of 10 Mbps. It is considered to be a secure wireless technology since communication area is restricted to below about 10 cm. To suppress electromagnetic radiation, we adopted a baseband transmission scheme in which the quasi-static electric field is directly modulated by 10 BASE-T data signals. Since the spectra of the data signals are concentrated to below 20 MHz, the amplitude of the electric field rapidly decreases outside the communication area. This contributes to enhancing security of the communications system. In this paper, we explain a basic principle of the short-range wireless communications technology. Since baseband data signals are carried by the quasi-static electric field, the quality of the communication is easily degraded by the existence of the earth ground. To isolate the communications system from the earth ground, we introduce a novel electro-optic sensor to receive the quasi-static electric field. With the electro-optic sensor, stable data communication is possible at 10 Mbps via dielectric materials, such as a wooden table.

A new technique to estimate the Poynting vector distribution from near-magnetic-field measurement is proposed. To calculate the Poynting vector, both electric and magnetic field should be known. In the proposed method, only magnetic-field measurement of three orthogonal axes is required. Electric field is estimated from the measured magnetic field by using the Maxwell's equation. The modified Yee cell is employed to estimate electric field from the measured magnetic field. Finally, the Poynting vector is calculated from the measured magnetic field and the estimated electric field. Since the proposed method enables us to understand propagation direction of electro-magnetic energy, it can be utilized to locate an emission source and to investigate a mechanism of undesired emission. Experiments are carried out to discuss the accuracy and to validate practical usefulness.

In this paper, a new heuristic algorithm is proposed to optimize the power domain clustering in controlling-value-based (CV-based) power gating technology. In this algorithm, both the switching activity of sleep signals (p) and the overall numbers of sleep gates (gate count, N) are considered, and the sum of the product of p and N is optimized. The algorithm effectively exerts the total power reduction obtained from the CV-based power gating. Even when the maximum depth is kept to be the same, the proposed algorithm can still achieve power reduction approximately 10% more than that of the prior algorithms. Furthermore, detailed comparison between the proposed heuristic algorithm and other possible heuristic algorithms are also presented. HSPICE simulation results show that over 26% of total power reduction can be obtained by using the new heuristic algorithm. In addition, the effect of dynamic power reduction through the CV-based power gating method and the delay overhead caused by the switching of sleep transistors are also shown in this paper.

The optimization of polarimetric contrast enhancement (OPCE) is a widely used method for maximizing the received power ratio of a desired target versus an undesired target (clutter). In this letter, a new model of the OPCE is proposed based on the Fisher criterion. By introducing the well known two-class problem of linear discriminant analysis (LDA), the proposed model is to enlarge the normalized distance of mean value between the target and the clutter. In addition, a cross-iterative numerical method is proposed for solving the optimization with a quadratic constraint. Experimental results with the polarimetric SAR (POLSAR) data demonstrate the effectiveness of the proposed method.