To successfully examine the RF design challenge, it is important to first examine a “traditional” RF design flow. The term “traditional” is meant to convey the flow is a common solution for many cutting-edge companies that had no software tools to help them. It is fair to say many of these design flows were established years ago, before software tools gained strength in the RF specialty.

This traditional RF design process is most easily identified in its use of DXF file transfer to bridge the RF and PCB design gap (FIGURE 1). But there are real problems with using primitive shapes in an advanced PCB design software package. Designers often have to “trick” the software system by copying the primitive objects into component geometries, or by trying to manipulate the shapes as area fill objects.

In addition, the primitive shapes cannot be easily modified. And if they are modified, design rule checks (DRCs) can’t be fully exercised, introducing instability into the design. In short, designers are left trying to use software methods never intended for RF design.

Even for the many RF design companies that have navigated their way through these issues, one glaring problem remains: There is no schematic. This means there is next to no control over the connectivity, and the presence of a schematic for the PCB portion of a mixed RF-digital-analog design becomes almost useless because the schematic and layout cannot be synchronized without dangerous workarounds. Reverse-engineering solutions can help these issues, but even then, the layout-driven design process can be messy and time-consuming. In the end, designs are difficult to reuse and only partially archived.