Analog ASIC FAQs
Bob Frostholm — JVD, Inc
FREQUENTLY ASKED QUESTIONS
Q: What is a “pure analog” ASIC design?
A: Pure analog ASICs compile multiple analog functions, such as amplifiers, power management, analog-to-digital converters (ADCs), and digital-to-analog converters (DAC) on a single chip. Generally, they do not incorporate digital processor or memory functionality.
Q: When is it appropriate to create an analog ASIC, rather than design the same functionality using standard analog devices?
A: Analog ASICs make the most sense when they are used instead of multiple single-function analog devices such as dc-dc converters or low-dropout regulators (LDOs), amplifiers, comparators, ADCs, and DACs. A collection of these chips can be costly when purchased individually, and any analog ASIC manufacturer will agree that these functions are relatively easy to integrate for a specific application.
Q: What are the engineering tradeoffs associated with analog ASICs?
A: Cost reduction is perhaps the main driver for analog ASICs. Since standard-product analog ICs tend to be single-function devices such as op amps, LDOs, dc-dc converters, ADCs, and DACs, multiple packaged parts can be expensive (Fig. 1). They also can consume a lot of board space compared to a single analog ASIC.
Higher reliability is also a consideration—the fewer the number of devices in a system, the greater the long-term reliability. Also, some companies see intellectual property (IP) protection as a reason to cloak their designs in analog ASICs, not wanting their competition to see what or how they are doing it.
Finally, product obsolescence protection is a consideration. Many analog systems can remain in production for years or decades, but standard-product analog IC companies periodically perform product line reviews and prune those devices that are no longer financially worth the effort to maintain in production.
Q: When should a company consider an analog ASIC semiconductor company?
A: Consider it from the standpoint of making an outsourcing decision. Generally an issue arises because the right kind of talent isn’t available in house. Companies often have internal digital design teams, but few will have analog teams. Outsourcing to a team of analog experts often leads to additional product features that were not previously considered and skill sets that go beyond the use of programmable logic devices (PLDs). That makes sense. Analog chip designers are hard to find and expensive to engage.
Q: What would be an example of such a situation?
A: One might be an industrial-control supplier with a successful controller product that uses discretes in the analog front end (AFE). The competition develops a product with competitive specs at a lower price. There’s no reason to change the digital portion of the design, but the bill of materials and manufacturing costs could be significantly reduced by replacing all the parts in the AFE with a custom analog ASIC.
Q: What analog functions could be integrated?
A: Here’s an actual example: a sensor interface for signal conditioning in medical applications. The custom part integrated:
- Switching voltage regulators (using outboard magnetics) to generate a 16-V bus and a precision 2.5-V reference voltage from a single 1.8- to 3.2-V coin-cell battery
- An 18-bit effective delta-sigma ADC that uses the 2.5-V reference
- A DAC with a programmable output of roughly 3 to 13.5 V
- A 10-μA constant current generator with 16-V compliance
- An eight-channel analog switch array to switch the 10-μA current source to eight external sensors in sequence
A: This is also an opportunity for simplifying design and implementation with an analog ASIC. Such a device can combine multiple switching regulators and LDOs with control circuitry (Fig. 2).
A: Analog does not scale the way digital does. An analog ASIC can easily integrate CAN Bus, SAE J1850, and K-wire and L-wire of SAE J1972 to develop an aftermarket product that executes diagnostics on any car, regardless of whether it came from a North American, Asian, or European carmaker (Fig. 3).
Q: How would a company interact with an analog ASIC supplier in cases like these? What design tools are necessary?
A: The process has very little in common with working with a big foundry. It’s more like working with another team inside the company procuring the ASIC. Once the dialog is initiated, the process involves conference calls and/or face-to-face meetings to clarify and document each performance requirement; generation of a rough budgetary cost for both tooling (a combination of nonrecurring engineering costs and physical tooling) and final unit pricing; and an initial rough schedule.
Once these parameters are approved, the two parties develop a detailed electrical spec. The datasheet for the actual analog ASIC becomes part of the development contract. Once the contract is signed, the analog ASIC company does the heavy lifting.
About Us: JVD is a privately-held company founded in 1982 whose mission is to achieve analog performance in their customers ASIC designs. Whether an ASIC, ASSP, or SoC design, JVD’s differentiated analog approach allows its customers to compete successfully in consumer, wireless, high-speed computing, power management, medical, industrial and networking applications. For more information, please visit www.jvdinc.com
Bob Frostholm, Vice President, Sales & Marketing
Email: bob [dot] frostholm [at] jvdinc [dot] com