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Multichannel apps stimulate 14-bit demand

Suppliers of data converters are increasingly developing dual high-resolution (14-bit) sampling analog-to-digital converters (A/D converters) in response to growing demand for multichannel applications, such as medical imaging and communications, as well as various spread-spectrum frequency and instrumentation apps.

Linear Technology Corp., Analog Devices Inc. and Datel Inc. are offering dual devices, and Texas Instruments Inc. plans to offer 14-bit dual A/D s in the near future. By this time next year, look for many more similar devices.

Maxim Integrated Products Inc., meanwhile, offers two-channel 14-bit A/D converters. (A dual A/D converter has two converters in one package, while a two-channel A/D converter has a two-channel multiplexer and two converters in one package.)

Linear Technology (Milpitas, Calif.) is kicking off 2005 with a 14-device family
of dual 14-bit A/D converters that offer 100-MHz, 110-dB channel isolation
performance at 445 milliwatts of total power consumption. The LTC2299 family is
said to provide excellent channel-to-channel isolation while achieving extremely
low power consumption. At 445 mW, or about 222 mW per channel, the 80-Msample/second LTC2299 consumes less power than slower competitors, the company said. The device is particularly suited for basestation applications, achieving a 73-dB signal-to-noise ratio (SNR) and 85-dB spurious free dynamic range (SFDR) at 70 MHz. For higher intermediate frequencies (IFs), it offers 72.6-dB SNR and 80-dB SFDR up to 140 MHz.


Click here to see the complete LTC2299 story at eeProductCenter.

Datel's ADSD-1410 A/D converter differs from the rest of the pack in that the
part is offered as a single multichip hybrid module that has two internal,
separate A/D converters with support circuitry


Click here to see the product review on Datel’s ADSD-1410 at eeProductCenter.

By contrast, the products offered by ADI, Linear and Maxim Integrated Products are fully monolithic A/Ds. The big difference between monolithic A/D converters and hybrids is that the hybrid solution includes as many as 20 components, while the monolithic device requires the addition of many external components to perform the same functions.

Many dual 14-bit multichannel A/Ds are available now, especially at high speeds.
Analog Devices' AD9248 appears to be the fastest dual 14-bit sampling A/D
converter on the market. ADI (Norwood, Mass.) started volume shipments in
December on the part, which had sampled for about a year. The company claims to
be the first on the scene with a 14-bit dual A/D converter supporting speeds of
20 Msamples/s to 65 Msamples/s, with power consumption of 300 mW/channel at 65
Msamples/s.

Click here to see the complete writeup on ADI’s AD9248 at eeProductCenter.

With a series that samples at up to 5 Msamples/s, Maxim Integrated Products
(Sunnyvale, Calif.) lays claim to the smallest two-channel 14-bit A/D converter
series in its class. Measuring 7 mm2 in a 48-pin TQFP, the MAX1318, MAX1322 and
MAX1326 offer two independent input channels. The A/Ds convert two channels in 2
microseconds.

Click here to see the complete product brief on Maxim’s MAX1318, MAX1322 and MAX1326 at eeProductCenter.

Linear Technology also offers its LTC1407A and LTC1407 two-channel, 14-bit A/D
converters, featuring simultaneous sampling at 3 Msamples/s. These fast serial
converters are available packaged in a 10-pin MSOP, which is less than half the
size of an SO-8, allowing the design of compact high-speed data acquisition
systems.

The LTC1407A achieves 73.5-dB signal, noise and distortion and guarantees 14-bit
no missing codes. The small size, high speed and simultaneous sampling are said
to make the LTC1407 a good choice for medical applications, instrumentation,
multiphase motor control and narrowband I/Q demodulation.

The LTC1407A is powered from a single 3-V supply, and power dissipation is
typically 12 mW. When the device is not converting, power dissipation can be
reduced to 3.3 mW in nap mode, with the on-board 2.5-V reference remaining
active, and 6 W in sleep mode, with everything powered down. The two conversion
results are delivered sequentially to high-speed DSP serial ports via a
three-wire SPI interface. These features are said to support smaller,
lower-power designs for simultaneous sampling applications.

The LTC1407A and LTC1407 are available in the commercial and industrial
temperature ranges. Pricing begins at $7 each for the LTC1407A and $4 each for
the LTC1407 in 1,000-piece quantities.

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