An Interactive Internet Service That Provides On-line Circuit Design

Merrimac Industries Inc.
West Caldwell, NJ

As the Internet changes the world's concept of entertainment, information, finance, commerce and hundreds of other disciplines, it remains relatively unexplored by the RF and microwave industry for much more than catalog perusal. However, its potential for achieving some of the industry's most widely stated goals - relationship building, reduced time to market and vendor responsiveness - is as vast as it is for consumers. A recently initiated, innovative service called On-Line Co-Design™ is making a substantial leap in this direction. On-Line Co-Design allows users to actually design a product based on the company's Multi-Mix™ multilayer fabrication technology through a high speed Internet connection. It is the first use of the Internet for this purpose by the high frequency electronic community.

Manufacturers have made enormous strides during the last decade to develop more intimate, dynamic relationships with their customers. Entire corporate philosophies have been recreated to better serve commercial customers who have unrelenting demands for delivery, performance and cost. On-Line Co-Design is one of the latest services for narrowing the gap between supplier and customer.

On-Line Co-Design development was assisted by Hewlett-Packard's EEsof Division, whose design tools are used on-line by Merrimac's customer's designers. The service essentially allows designers to create circuits on-line, over the Internet, based on the company's Multi-Mix three-dimensional design and fabrication technology.

Multi-Mix is a microwave design and manufacturing process based on fluoropolymer composite substrates that are fusion bonded together into a planar, multilayer structure, as shown in Figure 1 . The fusion process provides a homogeneous dielectric medium that yields superior electrical performance at microwave and millimeter-wave frequencies. The bonded structures can contain embedded semiconductors, MMICs, etched resistors, circuit patterns and plated-through via holes.

The resulting circuit becomes a self-contained, surface-mount module that requires no additional packaging and can be placed on the circuit board automatically with standard pick-and-place equipment. The small-outline, low profile structure created using Multi-Mix technology is lightweight, and the surface-mount format is compatible with microstrip or coplanar waveguide.

Subsystems designed with Multi-Mix have produced savings in size and weight that are greater than an order of magnitude when compared to the same subsystem designed with conventional microwave fabrication techniques. The Multi-Mix process lends itself well to low or high volume production and allows modifications to be made to existing designs without extensive rework.

On-Line Co-Design makes it possible for designers to select and place RF components as well as specially shaped, dimensionally controlled multilayer active and passive circuit elements. The Multi-Mix circuit elements are represented by icons on a palette that may be interconnected on the schematic window. Once the circuit is simulated, performance can be analyzed, plotted and displayed.

On-Line Co-Design provides designers with a first-hand approximation of the performance of their Multi-Mix-designed circuit. Circuit dimensions and relative performance can be obtained in sufficient detail to make engineering decisions about proceeding further into optimization and production of an actual device.

On-Line Co-Design differs in several important ways from the fairly common practice of part building found at Web sites throughout the industry: The design is comprehensive since it is created with HP EEsof design tools linear simulation software rather than a simple algorithm designed to display a catalog part once electrical values are entered. The results obtained from the exercise almost invariably answer the question of whether or not Multi-Mix will satisfy the user's electrical, physical and RF requirements. In addition, On-Line Co-Design significantly reduces the time required to obtain a working prototype.

The goal in developing On-Line Co-Design was to create a conduit through which customers could work with the company's engineering department to create virtual circuits representative of how the Multi-Mix process could be applied to their specific design challenges. The results obtained on-line can be applied immediately to the development of actual circuits.

HP's EEsof Division, recognizing the value of demonstrating its design tools to potential new users through a media to which it had no access, has supported Merrimac in its On-Line Co-Design development. On-Line Co-Design is currently available only to key customers and is supported by dedicated engineering and information system staff at the company.

The user log-in environment is not much different from that of a corporate intranet, even though it is an Internet-based service, as shown in Figure 2 . The user accesses Merrimac's Web site, uses a password to log on to the On-Line Co-Design system from his or her browser and starts designing. In addition to the log-in sequence, security features are provided to ensure privacy and all files saved in the On-Line Co-Design server are both software and hardware protected. Once initiated, On-Line Co-Design is largely transparent to the user, with HP EEsof design tools the dominant display element as it would be if the software were resident on the customer's system.

The full element library of HP EEsof design tools can be accessed by the on-line designers as well as elements based on actual test data that represent product platforms and EM models used to create S-parameter data. As a result, predicted performance is very close to the measured performance. All of the elements found in off-the-shelf HP EEsof design tools software are available to the designer, including any signal processing function and interconnection technology. The icons are the same as commercial versions of design tools. The result of the designer's effort provides more than enough information to enable a decision to be made about continuing the process.

On-Line Co-Design requires a PC and telephone line to access the Internet at the user's location. While the on-line sessions can be conducted at the speeds available via a 56-kbps V.90 modem, the quirks of the Internet make ISDN, DSL, T-1 or other high speed alternatives highly preferable. Additional information may be obtained from the company's Web site at or via e-mail at

Merrimac Industries Inc.,
West Caldwell, NJ
(888) 434-6636.