Programmable Analog Functions Are Going Mainstream

Design flows require a new methodology and design philosophy to achieve the best results. Because the tools use higher-level system views of the analog functionality, designers need less experience in the cause and effect of circuit value and topology changes. The highly integrated components greatly reduce the need for critical matching, external component tracking, and tuning in manufacturing.

Stan Kopec, vice president of marketing at Lattice Semiconductor, claims that the programmable analog component market is still in its infancy, roughly equivalent to the state of programmable logic in the late 1970s or early 1980s. The market is still developing. Designers must change methodologies and design philosophies to make the market grow faster.

The first big necessary change is to bring a methodology like the programmable logic design tools to the analog design space. Designers require a suite of design-entry tools that enable the easy development of designs that take advantage of available silicon capabilities. Designers have to become familiar and comfortable with the idea of downloading a bitstream via a JTAG port to alter the circuitry.

Higher-level tools, instead of just Spice, let the designer program functions in silicon to make the final functions. The higher level of integration reduces component variability and makes the design much less sensitive to the parasitics and layout variables. The integrated components also improve tracking because almost everything is on the same substrate, minimizing temperature and voltage differentials. The integrated parts make the problem easier to solve and conquer.

An appropriate combination of tools and silicon can reduce the level of expertise needed to design analog circuits and allow designers with minimum knowledge of circuit characteristics and complexities to create working analog subsystems in a short time. Just like programmable logic parts, programmable analog arrays offer quick confirmation and verification of the design. All programmable arrays have associated design kits and evaluation boards to let the designer quickly check the analog system performance in a real circuit.

The overriding problem with generic analog arrays is that they may be a good idea but might not be economically feasible. The flexibility costs $2 to $8 per part. Also, designers can't have full-accuracy analog functions, which are application-specific, in a general-purpose analog array. Nevertheless, the latest programmable analog function blocks provide very high performance. Some of the parts even permit for on-the-fly reconfiguration. This ability to change circuit parameters and topologies as needed means that the designer no longer has to trade off specific functions and performance for cost or general applicability in the system.