By Bonnie C. Baker. Texas Instruments

Designers are under constant pressure from both consumers and competitors to manufacture products on time. Product planning and implementation are critical in this era of rapid development. While it is important to proactively address implementation issues, many companies often overlook or even skip many steps during the planning phase. A key step in the planning phase is design creation and design verification. Electrical and printed circuit board (PCB) layer computer simulations are an important part of design work verification.

We can use various tools provided by IC manufacturers to achieve various simulations. IC manufacturers help their customers achieve many ambitious goals by developing many tools that meet the needs of PCB designers. These tools include analog circuits, digital circuits, and board-level design tools.

Some design tools can help determine the circuit topology of many complex blocks, such as switching analog power supplies or analog filter design, while also displaying key circuit performance specifications. For example, you can create an ideal power supply circuit using a power design tool such as the online or downloadable version of Texas Instruments SwitcherPro™ (see Figure 1 ).

Figure 1 Power supply design tools provide components to assist in the overall design (1).

Power supply design tools typically allow users to create their own designs, starting with ideal specifications and a reasonable number of IC components. These tools can also fully analyze the minimum and maximum performance of the completed circuit, as well as the effects of loss components, maximum junction temperature conditions, circuit efficiency, and circuit loop stability. When PCB designers begin experimenting with board implementations, most power supply design software provides a bill of materials (BOM) and board layout recommendations.

Analog filter design software can also help PCB designers. You can find versions of this software on the websites of some analog IC manufacturers. For example, TI offers FilterPro™ as its analog filter design program. These tools offload the heavy lifting of filter calculations to the computer. Filter design software packages can often design some or all low-pass, high-pass, band-pass, band-stop (notch), and all-pass filters. The software helps define the filter specifications and response type. Once these variables are determined, the software can provide a complete circuit, including many auxiliary components.

Once a design has been created (either manually or using design software), it can be verified and fine-tuned with the help of a SPICE simulator. SPICE simulators, such as Texas Instruments’ TINA-TITM (1), help design and evaluate the performance of multiple subcircuits in an application ( Figure 1 ). In Figure 2  , the goal is to find the difference between the gains of two filters over frequency.

Figure 2. SPICE simulation comparing the frequency performance of two low-pass filter circuits.

There are many SPICE macromodel libraries for analog circuits, I/O buffer information specifications (IBIS), and digital evaluation bond scan description language (BSDL) models. All of these models are available on most IC manufacturers' websites. In addition, there are various calculators available for download.

In summary, PCB designers have a wide range of tools to choose from that can help smooth the design planning and creation process. Although the answers provided by these tools cannot eliminate the breadboard stage, they can quickly provide you with some proven solutions for lab use—ultimately shortening your time to market.

References

1. SwitcherPro™ Switching Power Supply Design Tool: www.ti.com/switcherpro-ca .
2. FilterPro™ analog filter design tool: www.ti.com/filterpro-ca .
3. TINA-TI™ SPICE-based analog simulation program: www.ti.com/tinati-ca .