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14-bit A/D reaches 190 Msamples/s

Dallas — Texas Instruments Inc. (TI) unveiled a 14-bit, 190 Msamples/second analog-to-digital (A/D) converter that is said to provide strong dynamic performance and low power dissipation.

The ADS5546 offers 73.2 dBFS signal-to-noise ratio (SNR) and 84 dBc spurious-free dynamic range (SFDR) at the maximum sample rate of 190 Msamples/s with an input frequency of 70 MHz for wireless communications, video and imaging, test and measurement (T&M), and instrumentation applications.

“The ADS5546 features best-in-class dynamic performance, only 1.1 W total power dissipation and small 7 x 7 mm QFN packaging,” said Kent Novak, general manager for TI's high-speed products.

The A/D converter offers interface flexibility with user-selectable CMOS or double data rate (DDR) low-voltage differential signaling (LVDS) outputs.

The device includes an internal sample and hold, low-jitter clock buffer and internal or external reference capability. It also provides a unique set of value added features, such as programmable power scaling and user-selectable output timing and level controls, according to Novak.

The converter operates from a single 3.3 V supply and is specified over the industrial temperature range of -40°C to +85°C.

 
 
See Block Diagram

The ADS5546 is sampling now, with volume production scheduled for 2Q 2006. The device comes in a 48-pin QFN package and is priced at $72.50 in 1,000-piece quantities (suggested resale pricing). Evaluation modules are also available. Click here for the ADS5546 data sheet.

Texas Instruments Inc. , 1-800-477-8924, www.TI.com.

TI claims these next-generation 14-bit devices provide breakthrough performance in terms of sampling speed, power consumption, package size, SNR and SFDR performance.

A key attribute of the ADS5546 is that it allows the user to select one of two interface modes on the same output pins — CMOS or DDR LVDS. “This is the first time an A/D converter offers both of these interfaces on the same output. The DDR LVDS option will reduce the wiring complexity of the customer's board on top of reducing the package size of the A/D converter,” said Yiannis Papantonopoulos, TI's systems and applications manager for high speed A/D converters. Similar devices with standard LVDS outputs require 28 different signal lines (14 x 2) — and now TI is achieving this with 14 pins, he said.

Papantonopoulos also believes TI has pushed the performance envelope regarding SNR (73.2 dB) and SFDR (84 dBc) with an input frequency of 70 MHz, as well as power consumption (1.1 W at 3.3 V).

If you look at the Competitive Landscape slide below, at 190 Msamples/s, the closest competing device to the ADS5546 delivers SNR of only 68 dBFS. “We are pushing 74 dBFS, which is almost 6 dB better. No one else is doing this at 14 bits,” Papantonopoulos said

All of these features will ultimately boost system reliability, especially in communications applications like wireless infrastructure systems, according to Papantonopoulos.

 
 
See related Competitive SNR Chart

The higher SNR enables true multicarrier capability, reduces the number of signal chains, lowers power requirements, increases performance and enables power amplifier linearization in transmitters, Papantonopoulos said. “A large input bandwidth- typically several times the wanted signal bandwidth is needed for power amplifier linearization. Most A/Ds can't be used for this because they don't have the bandwidth,” he said.

The signal chain for wideband applications can be simplified or even reduced by a factor of two, which can ultimately produce large cost savings, Papantonopoulos said. Processing a really wideband signal might have necessitated splitting up the signal chain in two, requiring twice the amount of A/D converters, mixers, amplifiers, filters, etc. “All this can now be accomplished with one ADS5546. This device can capture ultra-wide signal bandwidths, while simultaneously delivering ultra-high SNR,” Papantonopoulos said.

High SNR and SFDR also translate to extra sensitive T&M applications that are more accurate when analyzing wave forms. They also lower the magnetic field energy in medical applications and in combination with the high sampling speed will also improve image quality in high-end diagnostic equipment, Papantonopoulos said.

This 14-bit A/D converter from Analog Devices Inc. (Norwood, Mass.) is also intended to simplify basestation receiver designs. The AD9445 provides SFDR above 80 dBc and a SNR of 72.5 dBFS at input frequencies up to 300 MHz.

Click here for more details on ADI’s AD9445 at eeProductCenter.

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