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No leap of faith required here — Datel claims 14-bit A/D converter hybrid approach makes the most sense

Mansfield, Mass. — Datel Inc.'s ADSD-1410 is a contemporary, analog-signal-processing (ASP), multi-chip module (MCM). Technologically, the ADSD-1410 uses active laser trimming of thin-film resistors to weave different semiconductor chips — fabricated using different semiconductor processes — into a single, high-speed, ASP function that exploits the best performance features of each chip and each process technology.

Functionally, the ADSD-1410 is a dual, 14-bit, 10 MHz, sampling analog-to-digital converter (A/D converter) with buffered outputs. It has two input channels (A and B); two wideband (30 MHz) sample-hold (S/H) amplifiers; and two, independently clocked, 14-bit 10 Msamples/s A/D converters.

The ADSD-1410 is housed in a single, 28-pin, double-DIP, ceramic package. The unit employs a proprietary gate array that provides all the timing and control logic necessary to operate each converter from a single, edge-triggered, start-convert pulse. Consequently, both the A/D converters can be run independently at 10 MHz each, and alternating blocks of data can be clocked from the three-state output buffer continuously at 20 MHz.

Within the ADSD-1410's single-package multi-chip layout, Datel's designers have optimized signal-return and analog-digital-ground paths as well as provided localized capacitive decoupling to obtain 150µV rms noise levels. Consequently, signal-to-noise ratio (SNR), one of the most important specifications for imaging applications, is specified at 78 dB. Additionally, the use of all high-bandwidth analog components results in a total harmonic distortion (THD) of -80dB.

Applications for the ADSD-1410 include numerous high-end imaging applications (digital X-ray equipment, digital telescopes, military imaging, etc.) and two-channel in-phase and quadrature (I/Q) applications in communications, radar and sonar. The ADSD-1410's large-signal input bandwidth (20 MHz) also makes the product an excellent choice for multi-channel, fast fourier transform (FFT)-based applications such as spectrum analyzers.

The ADSD-1410 consumes just 1.7 W from its three supply rails of ±5 V and +15 volts. The unit is specified for operation over either the commercial or military temperature ranges. Contact Datel for military “high-rel” screening.

Pricing in 500-piece quantities is $482 for the ADSD-1410MC (0 to +70°C), and $732 for the ADSD-1410MM (-55 to +125°C). Delivery for samples for either device is stock to two weeks. Production quantities are available in four to six weeks.

Click here for the ADSD-1410 data sheet

For more information, within the US, please call (800) 233-2765 or (508) 339-3000, and for
visit Datel, a subsidiary of C&D Technologies, on the web at: www.datel.com

Advances in monolithic processing and design architecture have now evolved to where analog and digital design sections can share the same die to provide higher resolution and conversion speeds. The ADSD-1410, a single multi-chip hybrid module with two internal separate A/D converters and supporting circuitry, is an example of this evolution.

In the 1980s and 1990s, hybrid manufacturers like Datel were still serving the higher bits/speed applications (12-, 14- and 16-bit at megahertz speeds). As single-chip monolithic solutions from the likes of Analog Devices Inc., Linear Technology Inc., Maxim Integrated Products Inc., and Texas Instruments Inc., emerged though, hybrids became a niche market, said Bob Leonard, marketing manager of Datel Inc. “Monolithics represented a lower-cost option than a multi-chip hybrid,” he said.

Analog Devices Inc.'s (ADI) monolithic equivalent in terms of sampling rate would cost $29.39 (1,000-pieces), compared to Datel's device, which sells for $482.00 (500 pieces).

The big difference between monolithic A/D converters and hybrid A/D converters is that the hybrid solution includes as many as 20 different integrated components, while the
monolithic A/D converter requires the addition of many external components to perform the same functions.

Despite the obvious cost differences, the hybrid A/D converter offers many other benefits over competing monolithic A/D converters though, Leonard said. Furthermore, designers need to consider the “total cost of ownership,” he added.

By offering these 15 to 20 components in a single package, for example, a designer now only has to pay once for screening and qualification if the application requires military qualified components, Leonard said.

Also, because hybrids are highly integrated devices, they enable faster time to market since the front-end design of the A/D converter is already complete, he said.

Customers face a “make-versus- buy” decision when it comes to hybrid and monolithic A/D converters, Leonard said. “They have to decide if the time to market issue, and the responsibility of 15 to 20 components working properly together, justify building the circuit themselves with monolithic designs,” he said.

Hybrids are like a sliding window on the marketplace — always staying ahead of monolithic processing, according to Leonard. “We take the best the monolithics have to offer, and then incorporate them with our own analog-expertise, while selecting the best support components,” he said.

Many monolithic A/Ds may only offer typical guaranteed temperature performance at +25°C and no guarantees for operation with external components, which takes a certain leap-of-faith to proceed ahead with them, Leonard said. “We provide 100% tested devices over temperature to our customers,” he said. The ADSD-1410MM provides an extended temperature range of -55°C to +125°C, while monolithic A/D converters may only provide a reduced +85°C upper temperature limit.

On behalf of monolithic A/D converters, Jon Hall, ADI's strategic marketing manager for high-speed converters, said low power consumption is usually an area where monolithic devices have a leg up over hybrids because of the process technology used to develop these products. ADI's AD9248-20 (20-Msample/s A/D converter) offers power consumption of .18 W, compared to Datel's ADSD-1419, which offers 1.7-W power dissipation. ADI (Norwood, Mass.) also makes hybrid-type A/D converters, Hall said.

Another benefit of the hybrid or SMT-based data converter, is that it can internally accommodate next generation devices, while maintaining its performance and pin-functionality while many monolithics have quickly become obsolete.

Many customers who tried monolithic A/Ds before coming to Datel complained that they were too noisy when incorporated into their system boards, Leonard said. In many cases, which the ADSD1410 exemplifies, we have the lowest noise floor and the best peak harmonic that may be absolutely crucial for a design, he said. “Our being able to manage the internal grounds and decoupling at critical points, leads to our noise performancewhile our peak harmonic achievements may be attributed to our component choices in the front-end signal conditioning,” Leonard explained.

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