This paper describes miniaturized broadband lumped-element in-phase power dividers. We first propose two types of miniaturized broadband lumped-element in-phase power dividers composed of two inductors, a resistor, and two capacitors. Next, we use a simulation to compare these dividers with conventional power dividers. The simulation results reveal that the proposed lumped-element in-phase power dividers can help miniaturize circuits (by decreasing inductances by about 30%, reducing the number of necessary capacitors by half, and decreasing necessary capacitances by about 30% as compared to conventional lumped-element dividers) and attain broadband frequency characteristics (by increasing normalized operating frequency bandwidths (f/f0) by about 80% as compared to conventional lumped-element dividers).

This letter proposes a simple combined coding and modulation based on super-orthogonal convolutional codes (SOCs) in order to support both coherent and non-coherent ultra-wideband (UWB) receivers. In the proposed scheme, the coherent receivers obtain a coding gain as large as the SOC while simultaneously supporting non-coherent receivers. In addition, their performance can be freely adapted by changing the encoder constraint length and the number of PPM slots according to its application. Thus, the proposal enables a more flexible system design for low data-rate UWB systems.

The linearity and noise required by GSM and UMTS receivers make the design of a CMOS mixer for these applications so challenging. A new technique for IP2 improvement in Zero-IF active mixers is presented in this paper. This inductor-less technique is based on canceling the parasitic capacitor of common source node of the switching transistors and synthesizing resistive impedance. Using this technique, a reconfigurable down converter mixer works from 900 MHz to 2.4 GHz is designed supporting GSM, DCS, PCS, UMTS and IEEE802.11 b-g standards. The mixer IIP2 is higher than 71 dBm in GSM and UMTS bands. The mixer conversion gain is higher that 12 dB in all frequency bands. The design is done in 65 nm CMOS technology and consumes 10 mA from a 1.2 V supply. The design meets the performance required for all mentioned standards, while its area and power is comparable with high performance single band mixers.

We have designed, fabricated and measured a second-order multibit switched-capacitor complex bandpass ΔΣAD modulator to evaluate our new algorithms and architecture. We propose a new structure of a complex bandpass filter in the forward path with I, Q dynamic matching, that is equivalent to the conventional one but can be divided into two separate parts. As a result, the ΔΣ modulator, which employs our proposed complex filter can also be divided into two separate parts, and there are no signal lines crossing between the upper and lower paths formed by complex filters and feedback DACs. Therefore, the layout design of the modulator can be simplified. The two sets of signal paths and circuits in the modulator are changed between I and Q while CLK is changed between high and low by adding multiplexers. Symmetric circuits are used for I and Q paths at a certain period of time, and they are switched by multiplexers to those used for Q and I paths at another period of time. In this manner, the effect of mismatches between I and Q paths is reduced. Two nine-level quantizers and four DACs are used in the modulator for low-power implementations and higher signal-to-noise-and-distortion (SNDR), but the nonlinearities of DACs are not noise-shaped and the SNDR of the ΔΣAD modulator degrades. We have also employed a new complex bandpass data-weighted averaging (DWA) algorithm to suppress nonlinearity effects of multibit DACs in complex form to achieve high accuracy; it can be realized by just adding simple digital circuitry. To evaluate these algorithms and architecture, we have implemented a modulator using 0.18 µm CMOS technology for operation at 2.8 V power supply; it achieves a measured peak SNDR of 64.5 dB at 20 MS/s with a signal bandwidth of 78 kHz while dissipating 28.4 mW and occupying a chip area of 1.82 mm2. These experimental results demonstrate the effectiveness of the above two algorithms, and the algorithms may be extended to other complex bandpass ΔΣAD modulators for application to low-IF receivers in wireless communication systems.

This letter proposes a new bandpass shielding enclosure (BPSE) for modern handheld communication devices. This enclosure is characterized by high transmittance at the specified wireless signal band and high shielding effectiveness (SE) outside this band. In addition, it has little influence on the impedance-matching bandwidth and antenna patterns of an internal antenna embedded inside the device. A prototype was created, simulated and measured. The simulated and measured results demonstrate the promising performance of this newly proposed shielding enclosure.

In this research, the performance degradation of the digital electronic equipment under electromagnetic (EM) disturbance was studied in order to investigate the interference of intra-equipment. To develop the evaluation method of the performance degradation, some communication indexes were measured under EM disturbance. From some experimental results, it is known that the performance degradation of the electronic equipment was estimated by the degradation of "through-put," one of the communication performance indexes. For further investigation of the interference of intra-equipment, the near EM field from a PCB of the electronic equipment and its performance degradation under EM disturbance were measured and compared. From the measured results, the relationship between near field measurement and performance degradation could be obtained in some extent. These facts enable us that the weak area under the EM disturbance application on PCB can be foreseen by measuring the near field emission from the equipment and vise versa.

This paper proposes an advanced hybrid network architecture and a comprehensive network design of the next-generation science information network, called SINET3. Effectively combining layer-1 switches and IP/MPLS routers, the network provides layer-1 end-to-end circuit services as well as IP and Ethernet services and enables flexible resource allocation in response to service demands. The detailed network design focuses on the tangible achievement of providing a wide range of network services, such as multiple layer services, multiple virtual private network services, advanced qualities of service, and layer-1 bandwidth on demand services. It also covers high-availability capabilities and effective resource assignment in the hybrid network. The cost reduction effect of our network architecture is also shown in this paper.

This paper describes a high power GaN-FET amplifier which is developed for wideband code division multiple access (W-CDMA) base stations. We design a bias network which is symmetrically arranged to the RF line (two way bias network) in order to reduce impedance at a baseband frequency of the multi-carrier W-CDMA signal. As a result, the amplifier with the two way bias network successfully suppressed memory effects. Therefore, the application of a DPD technique to the GaN-FET amplifier with the two way bias network demonstrates almost 20 dB linearity improvement in IM3 and considerable improvement in higher order IMD, resulting in low IMD of less than -50 dBc at the highest ever reported W-CDMA average output power of 76 W.

Transitions between a post-wall waveguide and a microstrip line are proposed as the key components for cost-effective millimeter-wave modules. A transition with a coaxial structure is investigated for LTCC laminated layers and 11.3% bandwidth for the reflection smaller than -15 dB is realized in 60 GHz band. The overall connector loss with 1 cm post-wall would be about 0.8 dB. The degradation due to fabrication error is also assessed. The transition in LTCC substrate fulfills electrical and manufacturing demands in millimeter-wave bands.

A multi-band burst-mode clock and data recovery (BMCDR) circuit is presented. The available data rates are 2488.32 Mbps, 1244.16 Mbps, 622.08 Mbps, and 155.52 Mbps, which are specified in a gigabit-capable passive optical network (GPON) [1]. A half-rate and low-jitter gated voltage-controlled oscillator (GVCO) and a phase-controlled frequency divider are used to achieve the multi-band reception. The proposed BMCDR circuit has been fabricated in a 0.18 µm CMOS process. Its active area is 0.41 mm2 and consumes 70 mW including I/O buffers from a 1.8 V supply.

A daisy chain of current-driven transmitters in inductive-coupling complementary metal oxide semiconductor (CMOS) links is presented. Transmitter power can be reduced since current is reused by multiple transmitters. Eight transceivers are arranged with a pitch of 20 µm in 0.18 µm CMOS. Transmitter power is reduced by 35% without sacrificing either the data rate (1 Gb/s/ch) or BER (<10-12) by using a 4-transmitter daisy chain. A coding technique for efficient use of daisy chain transmitters is also proposed. With the proposed coding technique, additional power reduction can be achieved.

This paper reviews our progress on the high-Tc superconducting (HTS) sampler development, covering from the circuit design to the latest experimental data in the sinusoidal and pulse waveform measurements. A computer simulation has revealed that our sampler circuit with an improved design enables waveform measurement with the bandwidth over 100 GHz even with the thermal noise at around 40 K. Using the HTS sampler circuits fabricated employing an improved layout, we demonstrated waveform measurements for sinusoidal signals with frequencies of up to 50 GHz, the upper limit of the signal generator we used, both in the voltage-input-type system with a high-frequency input line and in the current-input-type one with a superconducting pickup coil. In the pulse measurement using an on-chip sampler, we succeeded in observing pico-second-order-wide single flux quantum (SFQ) current pulses, suggesting the potential bandwidth of our HTS sampler of more than 125 GHz.

In this paper, theoretical properties of deinterlacer banks are analyzed. Deinterlacer banks are novel filter banks in the sense that a progressive video sequence is separated into two progressive video sequences of a half frame rate and, furthermore, interlaced sequences are produced as intermediate data. Unlike the conventional filter banks, our deinterlacer banks are constructed in a way unique to multidimensional systems by using invertible deinterlacers, which the authors have proposed before. The system is a kind of shift-varying filter banks and it was impossible to derive the optimal bit-allocation control without any equivalent parallel filter banks. This paper derives an equivalent polyphase matrix representation of the whole system and its equivalent parallel structure, and then shows the optimal rate allocation for the deinterlacer banks. Some experimental results justify the effectiveness of the optimal rate allocation through our theoretical analysis.

In this paper, the authors propose a circularly polarized printed antenna combining a slot array antenna and a patch antenna, with dual-band operation. The proposed antenna has good isolation performance, is compact, and has simple configuration. This antenna is composed of two parts, a patch antenna (for Rx) on the top, and a slot array antenna (for Tx) on the bottom, respectively. The element layout is such that the lower radiation element is not hidden by the upper one for wide observation angle. Hence, both radiation elements can naturally radiate the targeted polarization. Both slot array and patch antenna are fed by electromagnetically coupled microstrip line feed. With such a configuration, it is possible to efficiently obtain good isolation characteristics for both frequency bands. Furthermore, this antenna can be easily composed and it is not necessary to use any feeding pin or via hole. The target of this antenna is mobile communications applications such as mobile satellite communications, base-station of wireless LAN, etc. Here, the design techniques are discussed and the numerical and experimental analyses are presented.

This paper surveys and introduces propagation studies and models that are expected to contribute to the development of broadband wireless systems. The survey focused on theory-based propagation models, experimental measurement data useful for modeling, and transmission characteristic evaluations using propagation models. The survey did not attempt to cover all papers in the research fields, but rather took key papers for various relevant subjects and described them in some detail. The basic characteristics of multipath propagation are summarized from the viewpoints of narrow-band (NB), wide-band (WB), and ultra wide-band (UWB). Recent studies on spatio-temporal propagation models and the relationship between models and systems are introduced. To clarify the relationship between OFDM, which is a representative of wideband data transmission schemes, and wave propagation factors, problems due to large delay spread and large Doppler spread are highlighted. Finally, studies on UWB propagation measurement and propagation models are introduced.

Ultra-wideband pulse radars are promising candidates for 3-dimensional environment measurements by autonomous robots. Estimating 3-dimensional target shapes by scanning with an omni-directional antenna is an ill-posed inverse problem. Conventional algorithms such as the synthetic aperture method or parametric algorithms have a problem in terms of their calculation times. We have clarified the existence of a reversible transform between received data and target shapes for 3-dimensional systems. Calculation times are remarkably reduced by applying this transform because it directly estimates target shapes without iterations. We propose a new algorithm based on the transform and present an application example using numerical simulations. We confirm that the proposed algorithm has sufficient accuracy and a short calculation time.

The electromagnetic disturbance that leaks from ICT (information and communications technology) equipment might contain important information. Our measurements show that the information hidden inside of the electromagnetic disturbance can be monitored. First, we measured the level of the electromagnetic disturbance that leaks from laser printers and collected the waveform in the time domain. Then, we reconstructed the printed image from the data. As a result of our measurements, we found that at points 200 cm away or beyond it is difficult to reconstruct the printed image, and therefore the threat to electromagnetic security is not significant.

This paper reports on a fiber-optic system for in-building wireless communication/broadcast systems developed in Samsung Electronics. Our system delivers the third generation mobile system, satellite-digital multimedia broadcast, and wireless local access network services over a single strand of single-mode fiber or multi-mode fiber. We present the design issue and experimental results of the radio-over-fiber link.

We suggest a new minimum credit method for the dynamic bandwidth allocation in EPON. In the suggested method, to eliminate the unused transmission time-slot, each ONU requests no more than a predetermined maximum. We analyze the upstream channel resource wastage when traffic is light. Based on the analysis, we derive a minimum credit that eliminate the upstream channel resource wastage. The OLT estimates a traffic load and grants a minimum credit when the request is smaller than the minimum credit and traffic is light. Using simulation, we show the minimum credit discipline is superior than the existing methods in the mean delay and the frame loss rate.

We present here a simple technique for parametrization of popular biorthogonal wavelet filter banks (BWFBs) having vanishing moments (VMs) of arbitrary multiplicity. Given a prime wavelet filter with VMs of arbitrary multiplicity, after formulating it as a trigonometric polynomial depending on two free parameters, we prove the existence of its dual filter based on the theory of Diophantine equation. The dual filter permits perfect reconstruction (PR) and also has VMs of arbitrary multiplicity. We then give the complete construction of two-parameter families of 17/11 and 10/18 BWFBs, from which any linear-phase 17/11 and 10/18 BWFB possessing desired features could be derived with ease by adjusting the free parameters. In particular, two previously unpublished BWFBs for embedded image coding are constructed, both have optimum coding gains and rational coef ficients. Extensive experiments show that our new BWFBs exhibit performance equal to Winger's W-17/11 and Villasenor's V-10/18 (superior to CDF-9/7 by Cohen et al. and Villasenor's V-6/10) for image compression, and yet require slightly lower computational costs.