Enhanced high-frequency performance in a GaAs, self-aligned, n-JFETusing a carbon buried p-implant

C ion implantation has been employed, for the first time, to form the buried p-layer in GaAs, self-aligned, ion implanted JFETs. Comparable DC performance was seen for JFETs with C or Mg implants; however, C-backside JFETs showed superior high-frequency performance. High dose C-backside devices had a f_t of 28.3 GHz and a f_max of 43.2 GHz for a 0.5 μm gate length that were 28% and 46% higher, respectively, than comparable Mg-implanted JFETs. This enhancement is a result of the lower C_gs in the C-backside device resulting from he inherently low activation of the implanted C below the channel while the C still effectively compensated the tail of the Si-channel implant. This approach relaxes the trade-off between optimizing the DC and the AC performance for the buried p-implant in GaAs JFETs and MESFET's     

A digital automatic current control system based on an optimumassumed model

In this paper, a new ACR (automatic current regulator) scheme is introduced for brushless DC motors. It consists of a model closely resembling the motor and PWM inverter, an assumed rising pattern of the current, and a parameter estimation. Using the control scheme, the mean value of the motor current is kept at the reference current, and the transient current of the motor is kept equal to the rising pattern. For the disturbance, because of DC-line voltage change, the proportional path from the error to the duty cycle of the PWM signal stabilizes the ACR. This ACR scheme can be realized with a microcomputer     

A strategy for designing error detection schemes for general datanetworks

The author presents a five-step methodology that provides insight into the order in which errors should be considered when designing an error detection scheme, which types of error detection mechanisms are most effective, and which layer should be responsible for detecting a given type of error     

ATM switching and CPE adaptation in the North Carolina InformationHighway

This article describes the approach which has been used to implement a sector of the information highway throughout the state of North Carolina, with specific attention focused on the functionality of the equipment that comprises the North Carolina Information Highway (NCIH). This implementation of this information highway is based on ATM technology, used in both the switching systems of the network and the customer premises equipment (CPE). The large ATM switching systems provide the extensive number of connections that are predicted for the information highway. Multiple services can also be supported on the ATM switches. The information streams for these different services can all be converted into ATM format using the appropriate ATM adaptation layer for transport through the ATM network. By being able to support multiple services, and transport them across common ATM facilities, the ATM switches offer the NCIH great flexibility in the applications that can be provided to the customers. Use of the ATM technology allows the NCIH to provide the backbone for various services. To provide the distance learning service application and other applications on the NCIH, ATM capabilities are also being provided in CPE on a service multiplexer     

Models of visual word recognition: Sampling the state of the art.

A classification of models of visual word recognition is presented that facilitates formal comparisons between models of different formats. In light of the theoretical contributions to this special section, sets of criteria for the evaluation of models and strategies for model construction are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Data to frequency mappings in various MSK schemes

Minimum shift keying (MSK) is a digital modulation scheme which is suited to demanding applications requiring good bandwidth efficiency and error performance. It can be regarded as continuous phase frequency shift keying (CPFSK) with two signalling frequencies. In general, there is no unique mapping from the input data polarity to the particular signalling frequency during a given bit interval. The simplest formulation maps zeros of the data (marks) to the lower frequency, and ones (spaces) to the higher frequency. Other formulations of MSK employ more complex mappings. The article summarises the most commonly encountered mappings, then shows how to convert from one formulation to another by manipulating the input or output data. It is, therefore, possible to establish communication between different MSK modems employing different formulations of MSK by simple processing of the data     

The flagship is dropping behind the fleet [UK telecommunicationindustry]

Following privatisation in 1984, BT was mainly preoccupied with customer service, operating costs and business exploitation. BT, its competitors and the industry regulators now have to address major new network issues. Their success in meeting the challenges of the new technologies will have a major impact on the future of UK telecommunications equipment manufacturers. The author takes a hard look at the facts. He argues that duplicating local telecommunications plant is a mistake and should stop; price cap regulation produces the wrong result; and an authoritative engineering agency is needed to co-ordinate technology nationally     

Uniplanar techniques for monolithic microwave integrated circuits

`Uniplanar' techniques have recently been introduced for the design of monolithic microwave integrated circuits (MMICs). The aim of these techniques is to achieve a higher level of integration of circuitry and to overcome the need for through-substrate via holes and the related back-face processing steps. This is achieved by using coplanar waveguide (CPW), slotline, and miniature `thin-film microstrip' transmission-line media as opposed to conventional microstrip. The design and performance of a number of uniplanar MMIC couplers, amplifiers, and other test circuits fabricated using the GEC-Marconi (Caswell) foundry are described     

Phase II study of vinorelbine (Navelbine) in previously treated small cell lung cancer patients. EORTC Lung Cancer Cooperative Group

26 previously treated patients with progressive recurrent small cell lung cancer (SCLC) were given vinorelbine (Navelbine), 30 mg/m2 weekly. All patients had responded to first-line chemotherapy and were off therapy for at least 3 months. Partial response was observed in 4 out of 25 eligible patients (16%; 95% confidence interval 4-36%), stable disease in 7 patients and progression in 12 patients. The limiting toxicity was a non-cumulative leucopenia (80%, 32% WHO grade 3-4). Reaction at the site of injection was observed in 5 patients, causing treatment discontinuation in 2 cases. Other non-haematological toxicities were moderate. These results suggest acceptable toxicity and some antitumour activity of vinorelbine in pretreated SCLC patients.