July 26, 2016 Powering Up

Volume 4 | Issue 5

Computer circuits operate at low voltage, but most electronics of the world, like Supertex, operate at substantially higher voltages.

We all know the name of the central processing unit inside our computers. But if there were a promotional label for the high-voltage integrated circuits in many computer displays, palm digital accessories (PDAs), cellular phones and printers, it would read “Supertex Inside.”

Since 1976, the publicly held (NASDQ: SUPX) Silicon Valley company has specialized in the design and manufacture of high-voltage semiconductors for applications including imaging, medical ultrasound and telecommunications.

Supertex specializes in high-voltage complementary metal-oxide semiconductor (HVCMOS) integrated circuits and high-voltage double-diffused metal-oxide semiconductor (HVDMOS) transistors. Supertex’s business is about equally divided between custom and standard-catalogue high-voltage integrated circuits (ICs), including semiconductor foundry services.

High-voltage semiconductors are required as the interfaces of core digital circuits (microprocessors) and the real world of sensors, displays and printers. Modern computer chips typically operate in a range from 1 to 3 volts, while high-voltage ICs run as high as 450 volts.

“The trend in electronics is to improve performance, reduce size and reduce costs, leading to many new products for personal and business use,” says Peter J. Stonard, director of marketing at Supertex. “These same products must be user-friendly to humans, so the data displays and the inexpensive printers of today use high voltage, creating demand for high-voltage components.”

Power Lunch
“Everything we do, without exception to date, has used operating voltages that are uncommonly high in the semiconductor marketplace,” says Stonard. “We put the high-voltage devices first and then let the market decide how they’re going to use them.” Customers that have found uses for Supertex’s unique products include Minolta, Motorola, Palm, Philips, Scitex, Lucent Technologies, Nortel Networks, General Electric, Siemens, Toshiba and many other high-tech giants.

Approximately half of Supertex’s $80 million net sales for 2000 were from North America, with the rest about evenly split between European and Asian markets.

Medical ultrasound used in obstetrics/gynecology, gastroenterology and other specialties, is an important application for high voltage. Ultrasound is an analogue technology that reveals the internal structure of the human body by using reflected, above-audible sound waves. Special equipment converts those sound waves into a displayed image. Although the technology is decades old, today’s computer-enhanced ultrasound has much higher performance and resolution, in part because of transducers equipped with high-voltage ICs. This technology depends on Supertex high-voltage semiconductors to work affordably. The company’s new analogue switch array also helps reduce the size of the transducer probe.

The telecommunications industry needs high-voltage ICs to marry the past with the future. High-voltage ICs provide the needed interface between the computer circuitry in modern telephones and the public telephone system itself. “Supertex recognizes that the phone line has relatively high voltage on it, so we build components that switch the high voltage down to a lower voltage that’s compatible with digital circuitry,” explains Stonard.

Supertex’s product array includes a semiconductor hook switch that allows today’s slim telephone equipment to be backward-compatible with plain old telephone lines. Another Supertex product, the ringer chip, duplicates high-voltage ringer signals sent from the central office, but does so using cost-saving silicon to supersede a mechanical design.

Another crucial application for high-voltage ICs is in non-contact, ink-jet printers. These include the high-volume machines that print the color Sunday newspaper supplements, and inexpensive personal desk-top models. Both kinds move ink electrostatically at several hundred volts. “High-speed printing projects have a short cycle time. They can’t afford to make tooling for a weekly newspaper,” says Stonard. “They use very high-speed electrostatic printing, and Supertex is the supplier of choice for the high-voltage drivers for that print mechanism.”

Absolutely Fab
Supertex has recently invested $20 million in a new semiconductor fabrication foundry (“fab”) in San Jose to support the reliable, high-volume manufacture of its products. The new fab’s equipment includes plasma auto-etch and film deposition systems and photoresist coating equipment for better control and definition of critical layers of circuitry.

“The new fab allows us to increase production, reduce losses and develop new products while also running material for our foundry customers,” says Stonard.

The company employs about 400 workers, the majority of whom work inside Supertex’s new clean room wearing protective clothing to insulate semiconductors from the hair, dust and dirt particles that can contaminate silicon wafers.

About 50 product design engineers also work for the company, including a new group concentrating on telecommunications and emerging broadband applications.

The back-end processing operation, where dies are packaged and tested, takes place in Malaysia, Thailand and the Philippines. Telecommunications are one of the key future business opportunities for Supertex, in which fiber-optical micro-electromechanical systems (MEMS) need high-voltage drivers. MEMS components use semiconductor-scale structures to manipulate the light traveling through fiber optics, which in turn carry both the massive digital data traffic (the Internet’s backbone) and long-distance phone services. While someone else makes the MEMS device, Supertex high-voltage ICs are required to operate it.

The Light Ahead
Supertex is also engaged in the development of hot-swap power management products, which are used to maintain systems that are never powered down — Internet servers, for example. In personal electronics, such as cellular handsets, Supertex’s electroluminescent (EL) lamp drivers power single-color (monochrome) lamps. These are known for low audio noise (important because cell phones are held against the ear). Emerging white light-emitting diode (LED) drivers backlight new color displays for PDAs and the next generation cell phones. Several companies, such as Palm, are looking to Supertex for backlight driver parts for PDAs.

But perhaps the most exciting use for high-voltage ICs is in flat-panel displays for notebook computers and televisions. They don’t have the physical bulk of the traditional cathode ray tube (CRT), yet they rival CRTs in terms of visual and technical performance. As in other applications, high-voltage ICs are required to provide the interface between the low-voltage computer electronics and the display screen.

Supertex is working closely with display manufacturers to create high-voltage drivers to reduce the cost of the technology and expand the market for large screen, flat panel TVs. “Since the 1950s, people have dreamed of having a television set that looks like a framed photograph that you can hang on the wall,” Stonard says. “But only recently have flat panels for notebook computers migrated to desktop computers in the office and thin TV sets.”

He adds that the technology is available today, dominated by LCDs. But the price is about $300 per screen inch; a 30-inch flat panel television costs around $9,000. “We think the market will rapidly expand when the price of the set drops down to $100 per inch of screen,” Stonard says. “The reality is that if you were to open some of these emerging flat-panel television displays and look inside, you would see Supertex parts or parts that are made under Supertex licensed high-voltage technology.”

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