New tools support shift toward mixed-signal design

BANGALORE, INDIA: Until recently, the majority of integrated circuits (ICs) have been either purely digital or purely analog in nature. Based on this, early IC-based electronic systems were typically composed of a large number of relatively simple, discreet analog and digital chips mounted on, and connected by, one or more circuit boards.

As a result, digital and analog design teams worked in isolation. Today’s complex systems-on-a-chip (SoCs) typically integrate analog and digital circuitry, requiring implementation and verification of a combination of custom digital, memory, mixed-signal and analog blocks. Efficient, cost-effective development of such chips requires new electronic design automation tools.

Most analog designs are still largely full-custom and are crafted by hand. In addition to being time-consuming and prone to error, this transistor-level design style does not allow an existing design to be easily ported to a new foundry or process/technology node. Migration of such a design effectively requires the circuit to be re-implemented from the ground up, making it increasingly difficult to meet the reductions in time-to-market and development costs that the market demands. 

Mixed signal, on the contrary, allows designers to apply their expertise in defining the first circuit topology and makes porting to new nodes significantly easier. Integrating MEMS with analog and digital functions for instrumentation SoCs is a goal for many designers, because it offers the possibility of minimum cost and increased reliability.

It allows designers to optimize circuits to given specifications using mathematical optimization techniques and explore the specification boundaries of circuits and optimize analog circuits for lower power consumption and less area in a fraction of the time.  Mixed-signal designs have both analogue and digital subsections combined. Overall operation of the system relies on both functionality of each section, and interoperation between the analogue/digital sub-sections. 

Today, we are able to integrate multiple cores on an SoC, and the percentage of SoCs with mixed-signal content is growing. As the numbers of constraints are rising, there is a need for automated analog design and verification processes, and analog designers need full control of the design process.

So far, designers were able to identify analog and digital components for their products. However, with the consumer market driving the industry, things are changing. Now it’s all about mixed signal, which is getting more integrated.

Traditionally, mixed-signal technology allowed analog control and signal processing functions, such as amplifiers, ADCs and filters, to be combined with digital functionality, such as microcontrollers, memory, timers and logic control functions on a single, chip. However, recent advances in mixed signal technology have significantly simplified the implementation of such solutions by allowing many more functions to be integrated into a single device. 

The latest mixed-signal processes allow high-voltage functionality to be integrated into an IC alongside the relatively low voltages required for the more conventional mixed-signal functions. Compared to simulation-based techniques, mixed-signal design platforms dramatically reduce design porting time of analog circuit designs.

Products like Magma’s FineSim allows full-chip circuit simulation in mixed-signal design, enhancing SPICE-level accuracy for the analog and digital portions of the design. This ensures that the analog/digital interfaces are well simulated and verified before committing the chip to silicon.

New tools such as Magma’s Titan now enable optimization of analog circuit performance for a given process technology, pushing the design envelope for extreme performance. They enable efficient porting from one process technology to another, dramatically reducing turnaround time from several weeks to days. They also provide an alternative to time-consuming SPICE simulations.

To summarize, there is a positive confluence of events that the semiconductor market can leverage, a market that favors mixed-signal design, and recent tool advancements. Together, these make mixed-signal design truly alluring for designers worldwide. India, which has been a largely analog market, is already experiencing this shift with the taping out of a lot of new mixed-signal designs.

The author of the article is Vice President of Business Development, Custom Design Business Unit, Magma Design Automation, a leading provider of chip design software. The author can be reached at ashu@magma-da.com