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DesignTag digital core adds thermal signaling

Posted: 22 Jul 2008 ?? ?Print Version ?Bookmark and Share

Keywords:thermal signaling? IP core? active digital circuit element?

Algotronix Ltd has added 'thermal signaling' to DesignTag, an active digital circuit element that can be designed-in to ICs and FPGAs and detected through-package by an external scanner.

Algotronix, a consultancy spun out of Xilinx in 1998, has been offering DesignTag for over a year. DesignTag is intended to provide a method of identifying falsely labeled chips and supporting enforcement of IP core and CAD tool license agreements.

Empowering IP cores
DesignTag is a digital core coded with a customer-specific _signature_ that can be identified externally from a working device without needing to read the FPGA bit stream or take the chip out of its package. It works by modulating the power dissipation of the host device by around 5mW, which creates small temperature changes that are sensed by a thermocouple and decrypted by the reader software running on a PC.

Single or multiple tags can be present in a single chip and the scanner can read the serial number of each tag and use a separate web-based database to find out about a tagged chip. Security mechanisms allow DesignTag users to control who can detect their tag or to restrict elements of the information stored in the web database.

According to Algotronix the use of wirelessly readable tags would allow providers of IP cores to increase recognition for their work and increase the value of their cores and businesses. At present, chip labeling is done in ink at the final stages of manufacture and recognizes the IDM that physically makes the SoC or the maker of the FPGA, but not the IP contributors.

"The problem is how to deter theft and prove ownership of the design," said Tom Kean, managing director of Algotronix, in a statement.

The tag can also be used to confirm the design revision loaded into the FPGA or to signal internal status conditions, such as, when an overflow has occurred or a soft error was detected in memory. Signaling is done without interrupting the system operation or accessing package pins.

The DesignTag version shipping today for use with FPGAs is called DesignTag Red. This is available at an introductory price of $200 per code license. The DesignTag reader software is available separately at a cost of $800, and a starter kit comprising an evaluation board and thermocouple data logger, together with the reader software and licenses for five codes is shipping at $2,000. An ASIC/ASSP version of DesignTag will also be available; this is targeted at identifying rebranded semiconductors and will form a key mechanism to uncover parts that have been fraudulently remarked to enhance their value.

DesignTag Black is a version to cover the license enforcement needs of third-party IP core and CAD tool suppliers. It also provides a mechanism for IP core vendors to obtain product version or status information from IP cores embedded in a larger design. In this application the top-level designer is prevented from disabling or removing the tag by additional protection mechanisms.

Thermal signaling
Thermal signaling works by modulating the power dissipation of the host device in a predefined way. Heat pulses propagate through the chip package with low attenuation. The level of the power surge is selected to provide a package temperature rise of around 0.1C. The additional dissipation is typically 5mW, against an operational power consumption of greater than 150mW for a mid-sized Xilinx Spartan FPGA.

The DesignTag defaults to turn off after 15mins of operation. This has two effects. Firstly, it eliminates the small incremental power consumption, and secondly it makes detection by a fraudster more difficult as power has to be cycled.

The thermal output by the DesignTag takes the form of a 64bit code. A spreading code is used to control the heat generator using a circuit similar to a linear feedback shift register. The spreading-code generation circuit is based on the 'Tag ID', which acts like a cryptographic key, where each key results in a different pseudo-noise sequence.

The use of thermal signaling has several advantages over RF signaling in environments where EMI is being suppressed, Algotronix claims. However, the technology is not recommended for chips used with heatsinks or with forced-air cooling.

- Peter Clarke
EE Times Europe

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