A merged analog-digital circuit architecture is proposed for implementing intelligence in SoC systems. Pulse modulation signals are introduced for time-domain massively parallel analog signal processing, and also for interfacing analog and digital worlds naturally within the SoC VLSI chip. Principles and applications of pulse-domain linear arithmetic processing are explored, and the results are expanded to the nonlinear signal processing, including an arbitrary chaos generation and continuous-time dynamical systems with nonlinear oscillation. Silicon implementations of the circuits employing the proposed architecture are fully described.

The delta-sigma modulator (DSM) is an excellent choice for high-resolution analog-to-digital converters. Recently, a band-pass DSM has been a desirable choice for direct conversion of an IF signal into a digital bit stream. This paper proposes a quadrature band-pass DSM for digitizing a narrow-band IF signal. This modulator can achieve a lower total order, higher signal-to-noise ratio (SNR), and higher bandwidth when compared with conventional band-pass modulators. An experimental prototype employing the quadrature topology has been integrated in 0.6 µm, double-poly, double-metal CMOS technology with capacitors synthesized from a stacked poly structure. This system clocked at 13 MHz and digitized a 200 kHz bandwidth signal centered at 4.875 MHz with 100 dB of dynamic range. Power consumption is 190 mW at 5 V.

A fully balanced (FB) transconductor using two multi-input single-ended (SE) CMOS transconductors is proposed, where the transconductors use MOS transitors operating in a triode region for achieving a wide linear input-range. SE circuits are easier to design than differential circuits and inherently reject common-mode (CM) signals. The multi-input structure is used to make a CM feedback loop and to determine an output CM voltage. A high-output-resistance current mirror is used in converting a differential signal to a single-ended signal in order to achieve a high common-mode rejection ratio (CMRR) and a high output-resistance of the transconductor. The FB transconductor achieves a 2-Vpp linear input range at a 2.5-V power supply and consumes 1.74 mA. The output resistance of the FB transconductor is 2 MΩ. It operates at 2 V with a linear input-range of 1.2 Vpp and at 1.6 V with a linear input-range of 0.9 Vpp. A 2.5-V 2.5-MHz FB Gm-C filter using the FB transconductors achieved a CMRR of 45 dB and a passband IIP3 of 32 dBm.

In this paper, we discuss the access control in multimedia CDMA ALOHA protocol. We introduce a new algorithm for the access control based on Modified Channel Load Sensing Protocol (MCLSP) in an integrated voice and two different classes of data users, high bit rate and low bit rate, exist in a multi-code CDMA Slotted ALOHA system. With our new algorithm, we show that the throughput of high bit rate data users, as well as, the total throughput of the data medium can be optimized and take a maximum value even at high values of offered loads. We also investigate the performance when voice activity detection (VAD) is considered in voice transmission.

An AC coupling configuration for the active guard band filters is introduced for suppressing substrate coupling noise in analog and digital mixed-signal integrated circuits. With this method, a substrate-coupling-noise cancellation signal can be supplied to a ground-level substrate by using a single 3-V supply on-chip circuits. Noise was suppressed to a maximum of less than 0.05 from 100 Hz to 2 MHz in a 0.35-µm CMOS test chip. Both experiments and a simulation based on the substrate extraction model showed the similar dependence of the noise-suppression effect on the arrangement of the guard-bands and analog circuits. The simulation is thus effective for optimizing the arrangement to suppress noise effects when designing a chip.

Recently the applications of MEMS (micro electro mechanical systems) have made remarkable progress in many filelds. The optical application of MEMS is one of the most promising because it provides micro mechano optical devices, the key components for high-perfromance systems in optical communication networks and data storage devices. This paper disucces the impacts of MEMS techologies on optical systems. Furthermore, state-of-the-art exmaples of micro optical switches, pig-tailed tunable filters and two-dimensional MEMS optical scanners are described.

Simultaneous wavelength conversion of multi-WDM channels is expected to be a key technique in near-future networks. In this paper, 4-channel wavelength conversion using four-wave mixing (FWM) in a hybrid wavelength selector is successfully demonstrated. The wavelength selector consists of two four-channel spot-size-converter-integrated semiconductor optical amplifier (SS-SOA) gate arrays on a planar-lightwave-circuit (PLC) platform and two PLC-arrayed-waveguide-gratings (AWGs). As the wavelength selector has an individual SS-SOA for the wavelength conversion of each channel, there is negligible interference between channels. Four WDM channels with an 2.5 Gb/s modulation were converted from 1555 to 1575 nm. Clear eye openings and only a small power penalty of less than 0.5 dB were observed. The receiver sensitivity was -31 dBm at a bit error rate (BER) of 10-9.

A simple phase compensation technique with improved power supply rejection ratio (PSRR) for CMOS opamps is proposed. This technique is based on feeding back a current proportional to a derivative of the voltage difference between an output and an input, and does not require a common-gate circuit or a noise-free bias for the circuit. The proposed technique requires only two additional transistors, which are connected to the differential pair of transistors in a cascade manner, and the compensation capacitor is connected to the source node of the additional transistor. Experimental results show an improvement of more than 20 dB in the PSRR at high frequencies, comparing the technique with a Miller compensation. This technique also improves the unity gain frequency and the phase margin from 0.9 MHz and 17 to 1.8 MHz and 44 for 200 pF load capacitance, respectively.

10-Gbit/s monolithic receiver OEIC's for 1.55-µm optical transmission systems were fabricated using a stacked layer structure of p-i-n photodiodes and HEMT's grown on InP substrates by single-step MOVPE. A receiver OEIC with a large O/E conversion factor was obtained by adding a three-stage differential amplifier to a conventional feedback amplifier monolithically integrated with a surface-illuminated p-i-n photodiode. The circuit configuration gave a preamplifier a transimpedance of 60 dBΩ. The receiver OEIC achieved error-free operation at 10 Gbit/s without a postamplifier even with the optical input as low as -10.3 dBm because of its large O/E conversion factor of 890 V/W. A two-channel receiver OEIC array for use in a 10-Gbit/s parallel photoreceiver module based on a PLC platform was made by monolithically integrating multimode WGPD's with HEMT preamplifiers. The side-illuminated structure of the WGPD is suitable for integration with other waveguide-type optical devices. The receiver OEIC arrays were fabricated on a 2-inch wafer with achieving excellent uniformity and a yield over 90%: average transimpedance and average 3-dB-down bandwidth were 43.8 dBΩ and 8.0 GHz. The two channels in the receiver OEIC array also showed sensitivities of -16.1 dBm and -15.3 dBm at 10 Gbit/s. The two-channel photoreceiver module was constructed by assembling the OEIC array on a PLC platform. The frequency response of the module was almost the same as that of the OEIC chip and the crosstalk between channels in the module was better than -27 dB in the frequency range below 6 GHz. These results demonstrate the feasibility of using our receiver OEIC's in various types of optical receiver systems.

In this paper, new linearization techniques for low-voltage bipolar OTAs using hyperbolic function circuits are described. First, a design of an exponential-law circuit, which is a basic building block to compose hyperbolic sine and hyperbolic cosine circuits, is proposed. This circuit is simpler than the conventional circuit and is suitable for low-voltage application. Next, two linearized OTAs using the hyperbolic function circuits are presented. The transconductance is given by maximally flat approximation. Although designs of the OTAs are different, the output currents are given by the same expression. Finally, performance of the OTAs is discussed. The linear input voltage range of the proposed OTAs is almost the same as that of the conventional OTA. However, one of the proposed OTA has no more than two-thirds the power dissipation of the conventional one. The other has a superior high-frequency characteristic.

We report on a novel micromechanical photonic integrated circuits (PIC) for integrating free-space optical systems on a chip. Using polysilicon surface-micromachining technique, micro-optical elements, three-dimensional optomechanical structures, and microactuators are monolithically integrated on silicon substrate. We will discuss the basic building blocks of the micromechanical PIC, including XYZ micropositioners, 2-axis tilting micromirrors, scanning microlenses, and their integration with vertical cavity surface-emitting lasers. We will also discuss their applications in reconfigurable optical interconnect and active alignment in parallel free-space optical interconnect systems.

In this letter, a simple design of a discrete-time chaos circuit realizing a tent map is proposed. The proposed circuit can be constructed with 13 MOSFET's and 2 capacitors. Concerning the proposed circuit synthesized using switched-current (SI) techniques, the validity of the circuit design is analyzed by SPICE simulations. Furthermore, the proposed circuit is built with commercially-available IC's. The proposed circuit is integrable by a standard CMOS technology.

Leaky waves have been known for many years in the context of leaky-wave antennas, but it is only within the past dozen years or so that it was realized that the dominant mode on printed-circuit transmission lines used in microwave and millimeter-wave integrated circuits can also leak. Such leakage is extremely important because it may cause power loss, cross talk between neighboring parts of the circuit, and various undesired package effects. These effects can ruin the performance of the circuit, so we must know when leakage can occur and how to avoid it. In most cases, these transmission lines leak only at high frequencies, but some lines leak at all frequencies. However, those lines can be modified to avoid the leakage. This paper explains why and when leakage occurs, and shows how the dominant mode behaves on different lines. The paper also examines certain less well known but important features involving unexpected new physical effects. These include an additional dominant mode on microstrip line that is leaky at higher frequencies, and a simultaneous propagation effect, which is rather general and which occurs when the line's relative cross-sectional dimensions are changed. The final section of the paper is concerned with three important recent developments: (a) the new effects that arise when the frequency is raised still higher and leakage occurs into an additional surface wave, (b) a basic and unexpected discovery relating to improper real modes, which are nonphysical but which can strongly influence the total physical field under the right circumstances, and (c) the important practical issue of how leakage behavior is modified when the circuit is placed into a package.

We report on the fabrication and operation of all-NbN single flux quantum (SFQ) circuits with resistively shunted NbN/AlN/NbN tunnel junctions fabricated on silicon substrates. The critical current varied by about 5% in 400 NbN/AlN/NbN junction arrays, where the junction area was 88 µm2. Critical current densities of the NbN/AlN/NbN tunnel junctions showed exponential dependence on the deposition time of the AlN barrier. By using the 12-nm-thick Cu film as shunted resistors, non-hysteretic current-voltage characteristics were achieved. From dc-SQUID measurements, the sheet inductance of our NbN stripline was estimated to be around 1.2 pH at 4.2 K. We designed and fabricated circuits consisting of dc/SFQ converters, Josephson transmission lines, and T flip-flop-based SFQ/dc converters. The circuits demonstrated correct operation with a bias margin of more than 15% at 4.2 K.

An efficient procedure is presented to determine the implicit exact solution of an arbitrary nonuniform transmission line (NTL), and its first order approximation (F. O. A. ) as an explicit expression. The method of the solution is based on the steplines approximation of the nonuniform transmission lines and quasi-TEM assumptions. Using steplines approximation the NTL is subdivided into a large number of uniform line segments (steps). Using time-domain approach and invoking the boundary conditions at the discontinuities of the adjacent steps, each step is modeled as continuous time domain linear filter characterized by a transfer function. The frequency domain transfer function of this filter is then obtained for linear termination networks. For very large number of steplines this transfer function approaches transfer function of the NTL. In the next step a F. O. A. , as an explicit expression of the exact response will be obtained. This F. O. A. is more suitable for very short transmission lines which is often the case in integrated circuits and some of printed circuit boards. Then, the F. O. A. of the ABCD matrix will be obtained.

Today's complicated and heterogeneous telecommunication network environments need fully-integrated, cost-effective, user-friendly management systems. When developing such management systems in distributed environments, many telecommunication companies are carefully adopting CORBA and Java technologies. CORBA technology enables developers to create and manipulate distributed management system components easily while Java technology liberates human users from complicated and proprietary management system interfaces. In this paper, we propose a TMN-based integration framework for distributed network management by combining both CORBA and Java technologies. The framework generalizes a logically-layered architecture from the management agents layer to the user interface layer. It also provides generalized TMN management interfaces using inter-domain gateway systems for coordinating heterogeneous management protocols. By using these interfaces, TMN management function components can be easily constructed as CORBA objects to provide powerful TMN management services to administrators via user-friendly Web browsers. On the basis of this framework, we have designed and implemented a TMN alarm surveillance system which realizes our framework.

Up to now, a lot of efforts have been made for the management of telecommunication networks and equipment, but less effort has been made for the realization of higher-layer service and business management. Common Object Request Broker Architecture (CORBA) provides the infrastructure for interoperability of various object-oriented management applications in a distributed environment, and being widely used to develop distributed systems in many areas of information processing technologies. There are recently worldwide growing interests for applying CORBA technology for the realization of higher layer Telecommunication Management Network (TMN) management functions. In this paper, we propose a platform architecture for the efficient integration of CORBA technology within TMN framework, where CORBA-based management functions as well as TMN-based management functions can be realized efficiently. GDMO/ASN. 1 to IDL translator has been designed and implemented for translating TMN management information into OMG CORBA IDL interface. The CORBA/CMIP gateway has also been designed for realization of the interaction translation specification of JIDM task force with some additional extensions. Finally, we evaluate the performance of the CORBA-based network management system, and analyze the code reusability for the construction of the CORBA-based management system, in order to show the efficiency of the architecture.

In this paper, we consider an integrated voice and data system over CDMA Slotted-ALOHA (CDMA S-ALOHA). We investigate its performance when multi-code CDMA (MC-CDMA) is applied as a multi-rate scheme to support users which require transmission with different bit rates. Two different classes of data users are transmitted together with voice. Performance measurement is obtained in respect of throughput for data and outage probability for voice. Moreover, we consider the Modified Channel Load Sensing Protocol (MCLSP) as a traffic control to improve the throughput of data. As a result, we show that the MC-CDMA technique is an effective one to obtain good throughput for data users at an acceptable voice outage probability. Furthermore, we show that with MCLSP, the throughput of data can be improved to reach a constant value even at a high offered load of data users.

A 1.55-µm hybrid integrated wavelength-converter module was fabricated using a two-channel spot-size converter integrated semiconductor optical amplifier (SS-SOA) on a planar-lightwave-circuit (PLC) platform. Clear eye opening and penalty-free wavelength conversion were obtained at 2.5-Gb/s modulation with a wide wavelength difference of 46 nm. The module showed good characteristics including low insertion loss (0.1 dB), and high conversion efficiency (-0.2 dB). It also showed stable wavelength conversion for as wide as a 13 temperature range.

A 1.55-µm hybrid integrated wavelength-converter module was fabricated using a two-channel spot-size converter integrated semiconductor optical amplifier (SS-SOA) on a planar-lightwave-circuit (PLC) platform. Clear eye opening and penalty-free wavelength conversion were obtained at 2.5-Gb/s modulation with a wide wavelength difference of 46 nm. The module showed good characteristics including low insertion loss (0.1 dB), and high conversion efficiency (-0.2 dB). It also showed stable wavelength conversion for as wide as a 13 temperature range.