Analog to Digital Converters (ADCs) are used in many systems for data acquisition, data monitoring, as well as analog front-ends to antennas used in a variety of wireless, video and GPS devices.  Digital to Analog Converters (DACs) are used mostly in industrial systems to control or drive an electro-mechanical device such as a motor.  DACs are also used to drive analog video (VGA) screens still used in many computer monitors, appliances and industrial systems.

ADCs and DACs are problematic for most engineers.  The easiest way to deal with them is to buy standalone components from renowned companies and design them on the board next to the rest of the digital circuitry.  Suppliers of data converters provide helpful application notes and design guidelines to simplify the board design.  This approach works well for most systems. 

Some systems, however, have limitations as to board real estate, power consumption, cost or all of the above.  The problem becomes significantly more severe when the system requires multiple converters on the same board.  In the world of miniaturization, some systems do not have the required space for all the additional components.  Excessive power consumption is not only harmful for green systems or power sensitive handheld devices but it can degrade the performance of the system.  Finally, multiple converters can add tens, if not hundreds of dollars to the cost of the system.

One solution to this problem is to integrate the converters with the rest of the digital circuitry.  In most companies, mixing analog and digital on the same chip rings all sorts of alarm bells.  Cautious design managers avoid this approach like the plague.  There are many risks involved in mixed-signal designs but they can be successfully managed if one understands the source of the design risks and how to mitigate them.

The first source of risk comes from the converter IP itself.  Many converter designs have never been implemented in silicon or never been properly tested and characterized.  Using silicon proven and characterized IP will eliminate the risk originated from the IP itself. 

The second source of risk stems from the integration of the converters with the rest of the digital design.  In order to eliminate this risk, the engineer working on the integration must have mixed-signal design experience and must have successfully integrated analog functions with digital circuitry in the past.  This engineer should also have design guidelines for integrating the specific converter and preferably direct access to the mixed-signal designer of the converter. 

If you are building an engineering team to execute on a mixed-signal design, avoid taking shortcuts and believing that your competent digital team will be successful in integrating analog.  If you plan on working with an ASIC company to implement your mixed-signal design, you need to do your due diligence to reduce risk and insure success of your project.  At a time when cost is driving many project decisions, you need to avoid being “penny wise and pound foolish”.