Electronics & Computers

Conjugated Polymers Having High Charge-Carrier Mobilities

A three-year research project encompassed multiple studies of (1) polymer semiconductors that exhibit relatively high electric-charge- carrier mobilities and (2) applications of these polymers in electronic (including optoelectronic and nanoelectronic) devices. Although these polymers are of broad importance to all polymer semiconductor devices — including light-emitting diodes, photovoltaic cells, photodetectors, and electrophotographic imaging devices — the focus in this project was largely upon the use of these polymers in thin-film transistors, organic light-emitting diodes, and related light-emitting transistors.

Posted in: Briefs, Electronics & Computers
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Design Study of a C-Band Crestatron

A design study of a crestatron that would operate in the frequency range from 3 to 6 GHz (which overlaps with the C band) has been performed. The basic crestatron concept was developed during the 1950s. The present interest in crestatrons is spurred by the prospect of realizing compact, efficient, high-power, high-gain microwave transmitters in which crestatrons would be combined with low-noise, solid-state drivers into microwave power modules (MPMs). Such transmitters and MPMs could be attractive for applications in which there are severe constraints on volume and weight.

A crestatron is a variant of a conventional helix travelling-wave tube (TWT). Whereas a conventional helix TWT operates in an exponentially-growing-wave regime, a crestatron operates in a beating-wave regime, in which three constant-amplitude waves travelling at different phase velocities along its helix beat together to produce power gain. A crestatron potentially offers advantages over a conventional TWT of comparable power:

The circuit structure needed to support the beating-wave interaction of a crestatron can be considerably shorter than that needed to support adequate exponential growth in a conventional TWT. Thus, a crestatron is a higher-power-density device and thus, further, it may be useful in applications in which volume and weight must be limited. The geometric shortness of a crestatron circuit makes it possible to reduce the mass of the magnet and pole pieces needed to apply the magnetic field to guide electrons along the axis of the helix. The shortness also raises the prospect of capability of operation without an applied magnetic field, potentially leading to further reductions of weight and volume. A crestatron can put out a signal of usefully high power over a surprisingly broad frequency range with high efficiency. Although the gain of a crestatron is inherently lower than that of a conventional TWT of comparable power, low gain can be viewed as an advantage, in-as-much as it reduces circuit complexity, minimizes the need for high circuit attenuation to suppress instabilities, and eliminates the need for severs. [As used here "severs" is a noun denoting electrically conductive deposits on dielectric rods that support the helix (which is conductive). Severs serve as filters, helping to smooth out fluctuations in gain.] Low crestatron gain is compatible with a distributed-gain approach to design of an MPM in which a total system gain > 30 dB can be achieved by combining a crestatron with a high-power solid-state preamplifier. In this distributed-gain approach, the overall system noise performance benefits from the low-noise performance of the solid-state preamplifier while the overall system output-power performance benefits from the efficiency and high power capability of the crestatron vacuum electronic output stage. As in a conventional TWT, overall efficiency can be further enhanced with the introduction of a multi-stage depressed collector to recover energy from the spent beam electrons.

The degrees to which these advantages could be achieved were investigated in the design study, which was performed by use of CHRISTINE 1-D — a computer code developed previously for simulating the operation of a helix TWT in a large-signal regime. For example, large-signal simulations of a C-band crestatron operating at a potential of 5.850 kV and a current of 196 mA showed that this device could produce >250 W of power over a frequency span of 3 to 5.5 GHz. It was further shown that if the crestatron were to be combined with a two-stage depressed collector, the peak efficiency, reached at a frequency of about 5.2 GHZ, would be 64 percent. In contrast, a conventional TWT of similar power equipped with a two-stage depressed collector would exhibit efficiency of about 50 percent at this frequency (see figure). The crestatron as designed would also be a higher-power-density device, 40 percent shorter and 25 percent less massive, in comparison with the conventional TWT.

This work was done by DaviD K. Abe and Baruch Levush of the Naval Research Laboratory and David P. Chernin of Science Applications International Corp.

NRL-0029

Posted in: Briefs, RF & Microwave Technology, Electronics & Computers, RF & Microwave Electronics
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Static vs. Dynamic Detection of Bugs in Safety-Critical Code

In the never-ending quest to produce high-quality software, traditional dynamic testing plays a fundamental role. The weakness of dynamic testing is that it is only as good as the test cases. To be effective, a great deal of effort must go into writing or generating good test cases, and doing so can be very expensive.

Posted in: Articles, Articles, Electronics & Computers, Design processes, Computer software / hardware, Reliability, Test procedures
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Taking the Sting Out of Multiprocessor DSP Application Development

Systems engineers face a number of challenges when configuring and programming a complex, heterogeneous multiprocessor system of the type often used in digital signal processing applications. These include:

Posted in: Articles, Articles, Electronics & Computers, Design processes, Computer software / hardware, Systems engineering
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Using CompactPCI to Build Rugged Embedded Systems

The task-specific nature of an embedded system application typically defines a narrow scope of performance requirements. But the range of options for achieving those requirements are broad — from multicore processors and rugged single board computers (SBCs) to I/O devices and the bus systems that tie everything together. And the choices to be made are critical in their impact on cost, on performance efficiency in compute-intensive operations, and on the ability to function reliably in hot, cold, dusty or wet environments.

Posted in: Articles, Articles, Embedded Technology, Board-Level Electronics, Electronics & Computers, Embedded software, Durability
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Java Object-Oriented Embedded Database (ESC Booth 839)

McObject® (Issaquah, WA) has released Perst™, its all-Java object-oriented, open source embedded database that is compatible with the Android mobile device platform. Perst stores data directly in Java objects, eliminating the need for data-packing or unpacking code to map between the application's data model and the database's data model. Perst is a compact embedded database, with a core of only five thousand lines of code. This small footprint imposes little demand on system resources. Perst does not require administration and it supports transactions with the ACID (Atomic, Consistent, Isolated and Durable) properties.

Posted in: Products, Products, Embedded Technology, Board-Level Electronics, Electronics & Computers
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PCB Design Software

Sunstone Circuits (Mulino, OR) has released PCB123™ version 3.0, a complete circuit board design solution for the electronics design industry. PCB123 version 3.0's enhancements include real-time, bi-directional views of layout and schematic; full customization via the new PCB123 Software Development Kit; generation and updating of a dynamic bill of materials (BOM) as the user designs; and 3D design 'fly through' viewing features. As with previous versions, PCB123 version 3.0 is free.

Posted in: Products, Products, Embedded Technology, Board-Level Electronics, Electronics & Computers
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VME/VXS Board

Pentek, Inc. (Upper Saddle River, NJ) has released its Model 4207 high-performance VME/VXS board for digital signal processing and data-acquisition systems. The new board employs Freescale's MPC8641D Dual Core PowerPC AltiVec™ Processor and a Xilinx Virtex-4 FX Series FPGA for custom programming and gigabit serial I/O. The PowerPC processors perform 128-bit parallel processing of multiple data elements and deliver DSP floating-point processing rates up to 12,000 GFLOPS.

Posted in: Products, Products, Embedded Technology, Board-Level Electronics, Electronics & Computers
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8-bit Microcontrollers with Flash (ESC Booth 916)

Microchip Technology Inc. (Chandler, AZ) has announced two Baseline 8- bit Flash PIC® microcontrollers with non-volatile Flash Data Memory (FDM) in 8- and 14-pin packages. The microcontrollers have 41 bytes to 67 bytes of data RAM memory, an 8 MHz internal oscillator, a 1.125 ms Device Reset Timer (DRT), up to three channels of 8-bit Analog-to-Digital Conversion (ADC), and up to two comparators.

Posted in: Products, Products, Embedded Technology, Board-Level Electronics, Electronics & Computers
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32-bit Flash Microcontrollers (ESC Booth 306)

STMicroelectronics (Mansfield, TX) has released the STM32 Family of 32- bit Flash microcontrollers based on ARM® Cortex™—M3 core. The STM32 is offered in the STM32F103 performance line, with 72 MHz clock frequency for 32- bit devices, and the STM32F101 Access line, with 36 MHz clock frequency for 16- bit devices. Both lines offer 32K to 128K of embedded Flash memory. At 72 MHz executing from Flash, the STM32 consumes only 36mA.

Posted in: Products, Products, Embedded Technology, Board-Level Electronics, Electronics & Computers
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