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Self-calibration and oversampling technology allows new ADCs to contain more digital than analog circuitry. Self-calibration allows for looser tolerances on the analog circuitry and eliminates the need for potentiometers. It also allows the chip to adjust to changes over temperature and time. The increased percentage of digital circuitry provides more room for functions such as microprocessor interfaces. Oversampling is a digitally intensive conversion technique that is most adaptable to audio-frequency and low frequency signal environments.

The implementation of modular electronic assemblies with the use of board plug-in devices from a range of manufacturers can be achieved using Eurocard mechanical standards, and their use also permits the choice of a variety of packaging components that will be compatible with both the boards and each other. The Eurocard format is used in the U.S. by VME Bus and Multibus II products, and boards often come attached to a narrow, screw-in front panel so that they can be withdrawn from the subrack without the requirement of removing the whole front panel. A module can be placed into a Eurocard cassette or plug-in when the system requires more electronics than can be accommodated on a single board. A plug-in module gives the freedom of choice for any mechanical layout, and cassettes permit the insertion or withdrawal of a multiple-pc-board subsystem in one step.

A technology that has been in use for years, surface mount devices (SMD), is increasing board density, increasing functional capability, and lowering assembly costs. The transition to SMD requires careful planning because each step in the design process differs from established methods. SMDs are available in small outline, ceramic leadless chip carriers, and plastic leadless carriers. The problem of thermal coefficient expansion is being researched. SMDs can be purchased in bulk, on tape, in cartridges, or on rails. The pick and place equipment in use today are bench type systems, mass placement systems, and X-Y tables. Testing boards is more complicated, and testing approaches will have to change. Photograghs of SMD assembly systems, capacitors, LEDs, chips, trimmers, chip carrier sockets, connectors, and assemblies, and a table of SMD manufacturers are included.

New switch-mode power supplies have increased power density and improved performance. They are sold at lower prices and adhere to current standards. The designs have as much as three watts per cubic inch and ninety percent efficiency. Advances have been made in control integrated circuits with higher frequencies and lower costs. Current-mode technology controls phase shift, has increased reliability, and a more stable loop. Discrete components used by manufacturers include control integrated circuits, MOS field effect transistors (MOSFET), and surface mount devices (SMD). Photographs of a SMD module, power supplies, power supply circuit boards, and a modular motherboard and a table of switch-mode power supplies are included.

The inefficiency of conventional MOSFET devices using large dice made them too expensive to compete with bipolar transistors. The DMOS structures were the first power MOSFETs. VMOS transistors with vertical current conduction allowed current to flow from the back of the die to the source metallization on the top surface. Breakthroughs in DMOS technology in the early 1980s found manufacturers coining trademarks to reflect their special cell geometry and processing techniques. More recently, second and third generation devices are combining increased packaging density and short channel processes resulting in devices with significantly lower on-resistances per unit of silicon area.

Improved characteristics in power MOSFETs include reduced on-resistance and lower overall capacitance. Improvements have been most evident in low-voltage devices. Conductivity of a given chip size may be increased fourfold, drastically reducing heat-sinking requirements. Designers may select replacements on the basis of on-resistance or current ratings enabling use of a device with a smaller die. Die-size information is shown in a table, and a chart show the on-resistance values for first, second, and third generation TMOS transistors. A graph show the rise in case temperature during typical application to the efficiency of the latest chip designs. Another diagram illustrates a control circuit tailored for a blower motor employing a p-channel MOSFET for the power switch. The MOSFET's expansion into the power transistor market is likely to increase as designers come to realize the efficiency and economy of low-voltage MOSFETs.

The encapsulated dc-dc power converters of today offer a wide range of power ratings (from less than 1W to 50W) and a wide price range (from less than $15 to more than $150). Money can be saved in choosing a product if power needs are not overspecified. New component and manufacturing technologies enable converter manufacturers to put more power into smaller packages. Hidden costs incurred in choosing a more powerful unit than needed include decreased power efficiencies and loss of space on a pc board or in a chassis. A table lists a sample of the wide range of converters in small packages that are available. Advances in the smaller, more powerful converters include thick-film hybrid technology, custom, integrated circuits (ICs) and miniaturized magnetic components. Smaller converter size is obtained through the use of lower power levels and unregulated converters. Avoidance of load-regulation circuitry results in more power output as well as smaller package size. Some researchers say that unregulated converters are also more reliable in having a lower component count. Some applications require a regulated output; battery-fed units are an example. A number of converters combine regulation with a wide range of input voltages. Photographs of converters are included.

The high-density prototyping system consists of Unilayer II boards, wire-wrapping boards, multilayer boards, card cages, and custom engineering services. Six standard board geometries are available. As many as five 2-piece, 108-pin connectors may be used by each board. The largest board holds 465 ICs integrated circuits; the largest card cage holds 26 boards. Design engineers can submit wiring data and receive fully wired wire-wrapped or Unilayer II boards in three weeks. CAD engineering services can transfer the design to multilayer boards for volume production after the prototype has been tested and debugged. Prices range from $91 to $330. A photograph of the packaging system is included.

A densely packaged power supply produces high operating temperatures, stress, and decreased reliability and maintainability. The Navy Power Supply Reliability: Design and Manufacturing Guideline (NAVMAT) recommends a power density of one to three watts per cubic inch. A graph of the NAVMAT curves of power density is included.

A trend in printed circuit boards indicates that fifty percent of all boards will use surface mount devices (SMD) by 1990. The technology can reduce board sizes by as much as seventy percent and costs by fifty percent. It has increased density compared to through-hole components with more functional capability in the same package or comparable capability is smaller packages. A chart of world SMD consumption is included.

Custom IC design has been a problem in the past because of detailed geometric-mask design. Now with cell-compilers and the tools that support their use, programs are available that will convert user-defined functions and behavioral parameters that will allow the user to optimize custom chips. The article describes in detail the generation of customized cells, cell characteristics and interwiring of chip functions for compactness. The article contains several circuit diagrams that show different applications of cell layout.