The Birth of Analog Programmability

Rita Glover, EDA Today, L.C.
December 2002

EDA technology for FPGAs is making formidable advances as system-on-chip designs become more and more complex.  Behind this achievement is the fact that all the digital circuits in an FPGA can be reduced to simple building blocks — abstract logic functions such as latches and gates.

The circumstances in the analog realm have been quite different.  Analog designers need to provide for a much more diverse range of functions, and for every function an analog designer might want, there are many different ways to build it.  Thus, it has been difficult to automate analog design tools.  It's also been difficult to emulate the most important achievement of FPGAs, which is their ability to raise the level of abstraction to increasingly higher levels — up from logic gates to peripherals, and even up to on-board processors — the building blocks with which digital designers work.

Furthermore, system design efforts have been compartmentalized into hardware and software design, and traditionally these two worlds never come into contact until the first system board is built.  Until a prototype can be tested, it is uncertain as to whether the hardware and software will interact correctly.  But today the two domains are starting to merge, as complex, software-centric systems are being developed and verified with increasingly powerful design tools.

Automating Analog Design

Until now, the design of analog logic has scarcely been automated at all.  But as the cost of designing ASICs and SoCs mounts, momentum is growing to bring analog into the system-level interplay that is now taking place between chip architectures, software development environments, and hardware design tools.

Today, analog functions are being brought into the system-level design flow through a new generation of field-programmable analog arrays (FPAAs) introduced by Anadigm, Inc. (Campbell, California).  With FPAAs, designers can perform high-level design of analog functions by implementing Anadigm's configurable analog modules (CAMs).  This library of parameterizable analog functions allows designers to customize the functionality within the same C code that is used to drive the digital components in the system.

Anadigm’s new genre of dynamically reprogrammable FPAAs can be reconfigured on the fly for real-time control, updating, and manipulation of analog components under the control of the system processor.  This real-time control means that designers will now be able to use specialized analog logic for applications that formerly required DSPs.

Anadigm also provides sophisticated FPAA design tools that raise the level of abstraction at which analog design is done, to match the methodologies that prevail in the digital world.  This new paradigm for analog design eases the design process, so that non-specialists can rapidly create complex circuits that would require weeks or months of design work with discretes or ASICs.

The Market for Programmable Analog

Since system design is now on a faster design cycle, where more products must be put out per year with shorter lifecycles, designers want to avoid constant redesign and the time and cost associated with multiple development projects.  Total development cost is now a significant factor, and faster time-to-market is the mantra of competitive companies.

To stay competitive, system designers are turning to programmable systems.  Software forms the reusable and highly flexible base for new systems or modifications to existing systems.  Some of the applications for these new field-programmable analog arrays are:

Embedded Systems

Communications

Automotive

Intelligent Sensors
 

The Benefits to Designers

Engineers gain recognition for first-pass success with a new design.  The less the designer needs to worry about silicon/circuit design and is able to focus on software content, the better the chance of success.

The classic development process for embedded systems splits into two design flows after the specification stage.  The software flow involves a high-level programming language, and serial execution.  The hardware flow requires a high-level HDL, parallel execution, and an understanding of the structures involved.  Analog is treated as an afterthought, and often must be performed by an expert.

Merging the Hardware and Software Flows

To extract the maximum from reprogrammable systems, new mechanisms must be created to close the gap between these software and hardware flows.  Dynamic control requires an interplay between hardware and software elements.

This process has already begun with a crop of innovative young companies that all offer some type of real-time programmability:

Pioneers in programmable systems.  Source:  Anadigm, Inc.
 

To prevent these advances in the digital world from leaving analog even farther behind, Anadigm provides the programmability for the analog peripherals.  Under software-based programming, the central processor is able to assume run-time control over the FPAA configuration.  The RTOS running on the central processor takes control over these elements to provide a dynamically reconfigurable system, with real-time updating and repurposing of analog functions.

This technology brings analog design within reach of mainstream designers, and is an exciting new development on the EDA scene.

EDA Today, L.C.

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