Barcelona Design, for example, pushes the synthesis concept with Internet tools for op amp and interface design. But what Barcelona calls "synthesis" is really a process of presenting the designer with a model of an existing TSMC or Chartered Semiconductor cell, and asking him to tweak it with his own specifications. The design system will perform a simulation with the user's parameters, and report back whether the cell can be modified in its given process to meet the user's requirements. The user might go on to buy the RTL code, but it is a long way from the top-down abstractions available to designers of digital logic blocks.

Neolinear Corp.'s Neocell comes at synthesis from a different angle: It builds a cell from an unsized Spice netlist and design-rule input. Because it works best finding variations on an existing design, Gartner Dataquest analyst Gary Smith calls it a "process-retargeting tool."

Both Barcelona and Neolinear were represented on a Design Automation Conference panel in June at which semiconductor makers agreed that the so-called synthesis tools had some utility for novice designers. The tools do have utility, I agree, but mostly for simple analog circuits like amplifiers and line drivers. For really complicated stuff, such as data converters, you'll have to buy analog intellectual property from Antrim Design Systems or Nurlogic-which typically means you rent out their design teams.

Synthesis tools from Neolinear and Antrim, and one still in the wings from Analog Design Automation (ADA), use the "look-in-the-cell-library-for-something-I-can-use" model. Antrim proposes to shorten the search tree by putting it in the hands of an analog expert, a process the company calls a "directed search." ADA applies a fuzzy-logic variation to the process, and in the demo I saw at DAC, it looked pretty peppy. A retargeting tool might be available from ADA this fall, but the synthesis machinery-the kind that generates original structures-is at least a year away from introduction.

But the potential of these tools at big mixed-signal IC houses like Texas Instruments and STMicroelectronics is already attracting attention from high-powered investors.