Reduced state Viterbi differential phase detection of MDPSK signals

An improved differential phase detection scheme that uses a reduced state Viterbi algorithm (RSVDPD) is proposed for the reception of M-ary differential phase shift keying (MDPSK) signals. The transmitted sequence is estimated from the received signal phases only. The number of trellis states equals that of the signal constellation points M. The branch metric is computed by tracing back the surviving path connected to each state. The bit error rate (BER) performance with RSVDPD is evaluated using computer simulation for 4DPSK transmission in additive white Gaussian noise (AWGN) channels     

High performance 35 nm gate length CMOS with NO oxynitride gate dielectric and Ni salicide

The 35 nm gate length CMOS devices with oxynitride gate dielectric and Ni salicide have been fabricated to study the feasibility of higher performance operation. Nitrogen concentration in gate oxynitride was optimized to reduce gate current I/sub g/ and to prevent boron penetration in the pFET. The thermal budget in the middle of the line (MOL) process was reduced enough to realize shallower junction depth in the S/D extension regions and to suppress gate poly-Si depletion. Finally, the current drives of 676 /spl mu/A//spl mu/m in nFET and 272 /spl mu/A//spl mu/m in pFET at V/sub dd/=0.85 V (at I/sub off/=100 nA//spl mu/m) were achieved and they are the best values for 35 nm gate length CMOS reported to date.     

High channel mobility in normally-off 4H-SiC buried channel MOSFETs

We have fabricated buried channel (BC) MOSFETs with a thermally grown gate oxide in 4H-SiC. The gate oxide was prepared by dry oxidation with wet reoxidation. The BC region was formed by nitrogen ion implantation at room temperature followed by annealing at 1500°C. The optimum doping depth of the BC region has been investigated. For a nitrogen concentration of 1×10¹⁷ cm^-3, the optimum depth was found to be 0.2 μm. Under this condition, a channel mobility of 140 cm²/Vs was achieved with a threshold voltage of 0.3 V. This channel mobility is the highest reported so far for a normally-off 4H-SiC MOSFET with a thermally grown gate oxide     

Adaptive sparse system identification using normalized least mean fourth algorithm

Normalized least mean square (NLMS) was considered as one of the classical adaptive system identification algorithms. Because most of systems are often modeled as sparse, sparse NLMS algorithm was also applied to improve identification performance by taking the advantage of system sparsity. However, identification performances of NLMS type algorithms cannot achieve high‐identification performance, especially in low signal‐to‐noise ratio regime. It was well known that least mean fourth (LMF) can achieve high‐identification performance by utilizing fourth‐order identification error updating rather than second‐order. However, the main drawback of LMF is its instability and it cannot be applied to adaptive sparse system identifications. In this paper, we propose a stable sparse normalized LMF algorithm to exploit the sparse structure information to improve identification performance. Its stability is shown to be equivalent to sparse NLMS type algorithm. Simulation results show that the proposed normalized LMF algorithm can achieve better identification performance than sparse NLMS one. Copyright © 2013 John Wiley & Sons, Ltd.     

Fast clock synchroniser using initial phase presetting DPLL (IPP-DPLL) for burst signal reception

A fast clock synchroniser that quickly adjusts the initial phase of the DPLL output clock to the input signal (receiver detector output) at the beginning of acquisition is proposed for burst QDPSK signal reception. The synchroniser performance is given in terms of nondetection rate (NDR) of the unique word following the clock synchronisation preamble. Measured results clearly indicate that the proposed synchroniser achieves faster synchronisation than the conventional binary quantised DPLL clock synchroniser.<>     

Design for 2-D error feedback networks with identical coefficient sets

In realization of recursive digital filters with fixed point arithmetic, an error caused by roundoff arises. It is known that the level of the roundoff noise of an IIR filter tends to be high when the poles are close to the unit circle. Error feedback (EF) is an effective method to reduce the roundoff noise. It is desirable to design an EF network using as few parameters as possible in order to keep computational costs low. In this paper, we propose a method for designing a 2D EF network with identical coefficient sets. That is, the EF coefficients are divided into several subsets such that all the elements within each set have the same absolute value. In order to optimize the coefficient sets, we propose an algorithm by using the genetic algorithm. In the numerical example, we demonstrate the effectiveness of the proposed method.     

Combined code reuse scheme with two‐dimensional OVSF codes assignment algorithm for uplink multi‐user/multi‐rate block spread multi‐cellular CDMA

The two‐dimensional (2D) block spread code division multiple access (CDMA) can avoid the uplink multiple‐access interference with low‐complexity single‐user detection in a slow fading channel and, therefore, is very attractive. In the 2D spreading, orthogonal variable spreading factor (OVSF) is used for spreading; an important problem is how to efficiently assign the limited resource of OVSF codes to users with different data rates, while meeting the requirement of quality of service in a multi‐cell environment. In this paper, it is shown that the code reuse can improve the code reuse efficiency and the proposed code reuse scheme combined with code assignment algorithm can allow flexible multi‐rate uplink transmission. The computer simulation confirms that the proposed code assignment algorithm improves the code reuse efficiency while achieving lower blocking probability than traditional CDMA. Copyright © 2012 John Wiley & Sons, Ltd.     

Wafer-Level Integration Technique of Surface Mount Devices on a Si-Wafer With Vibration Energy and Gravity Force

This paper reports about a novel wafer-level integration technique of discrete surface mount devices (SMDs). It enables wafer-level mounting of plural kinds of SMDs on a silicon (Si)-wafer using vibration and gravity force. Deep holes with 400-m depth are formed on the surface of a Si-wafer by deep reactive ion etching process after general integrated circuit process for positioning of SMDs. A non-conductive adhesive (CYTOP) are coated on the deep holes and it is used to fix the aligned SMDs. SMDs are distributed on a Si-wafer mounted on vibration generator, and then a vibration is applied. The SMDs migrate due to the reduced friction between the wafer surface, and they drop into the holes on the silicon wafer. The size of the holes has an appropriate clearance to the size of SMD. In order to align two or more kinds of SMDs, sizes of the deep holes on a Si-wafer are adjusted to the size of each SMD. SMDs with the largest size are dropped into the holes first, and then the secondary large SMDs are dropped into the holes with the corresponding size. SMDs are finally connected electrically by wire bonding at the final step. In the experiment, two different sizes of SMD were successfully mounted into all the holes on a Si-wafer automatically. This technology will be a wafer-level process technology which is very promising to integrate two or more kinds of discrete elements.     

Outer-loop control of target SIR for fast transmit power control inturbo-coded W-CDMA mobile radio

A technique for obtaining outer-loop control of the target SIR for closed-loop fast transmit power control (TPC) is presented for turbo-coded wideband DS-CDMA (W-CDMA) mobile radio systems. The frame error rate (FER) of an intermediate decoding output in the turbo-decoder. i.e. before the final iteration stage is reached, is measured to control the target SIR. The bit error rate (BER) after the final decoding iteration can be maintained accurately at the prescribed BER value, e.g. BER=10^-6, without losing the tracking ability in the presence of slowly changing propagation channel conditions. Computer simulation results supporting this ability are reported