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Fast 16-bit A/D converter fits comm’s bill

Sunnyvale, Calif. — Maxim Integrated Products Inc. said it's setting a new industry standard in dynamic performance with its fastest (80 Megasamples/second) 16-bit analog-to-digital converter yet.

The MAX19586 offers superior dynamic performance including a noise floor of -82 dBfs, 80 dB SNR, and 96 dBc spurious-free dynamic range (SFDR) at an input frequency of 10 MHz (-2 dB input amplitude), said Ted Tewksbury, managing director of Maxim's high-speed signal processing business unit.

This performance is several dBs better than the competition in noise floor, SNR, and SFDR, Tewksbury said. It can also sample input frequencies beyond 170 MHz.

“Maxim leveraged its leadership data-converter technology to produce a high-speed ADC that advances the state of the art along both the dynamic performance and power axes,” Tewksbury said. “This remarkable performance is achieved at half the power required by the nearest competitor in a package that is one quarter the size.”

The MAX19586 is a 3.3 V A/D converter with a fully differential wideband track-and-hold (T/H) and a 16-bit converter core. Not only designed for excellent operation in the 2nd Nyquist region, the MAX19586 is
also optimized for use with high-IF input frequencies. This makes the part suited for high-performance digital receivers. The part has a 1.8-V digital supply voltage and a 2.56-V peak-to-peak full-scale input range.

“It is one thing to advance dynamic performance, but it is another thing to do that at almost half the power,” said Maher Matta, business manager for the company's high-speed converter products. At 1.1 W power dissipation, the MAX19586 uses 48 percent less power than the nearest competitor. This part is also packaged in a space-saving 56-pin QFN-EP, one fourth the size of that same competitor. This device is specified for the -40°C to +85°C industrial temperature range.

The performance of the MAX19586 is said to make it practical for high-performance broadband applications. Applications include cellular base-station transceiver systems (BTS), multicarrier and multistandard communication receivers, E911 location receivers,
antenna array processing, and high-end test and measurement instrumentation.

 
 
See related FFT chart

The MAX19586 provides the best combination of SNR and SFDR in the industry, according to Maxim. This allows system engineers to design communication receivers with extra sensitivity and aids the design of multicarrier receivers. The excellent 96 dBc SFDR performance eases filtering requirements, and less expensive filters reduce system costs. The large dynamic range can also be utilized to simplify system design by eliminating the need for variable gain attenuators (VGA) or automatic gain control (AGC) blocks in the receiver. This is especially important in systems where the receiver is expected to digitize both weak and strong signals. With over 80 dB of dynamic range, the system can capture both signals without having to change gain ranges.

In subsampling applications, the MAX19586 offers superior performance at high IF (77.2 dB SNR at an input frequency of 168 MHz), which allows system designers to eliminate RF down-conversion stages without sacrificing overall system performance. In instrumentation applications, the superb noise floor will quickly yield instruments with more measurement sensitivity than before.

 
 
See related SNR vs. Analog Input chart

The MAX19586 is available today. Pricing is
$59.25 (1000-up, FOB USA). Click here for the MAX19586 data sheet.

Maxim , 1-800-998-8800, www.Maxim-ic.com.

The 16-bit monolithic high-speed converter market is heating up — In addition to Maxim's MAX19586 unveiling, there have been two other recent announcements from Analog Device Inc. (Norwood, Mass.) and Linear Technology Corp. (Milpitas, Calif.)

 
 
See Maxim block diagram

While Linear Tech's LTC2208 clearly offers the highest sampling rate of the three devices at 130 Megasamples/second, Maxim's converter offers solid SNR and SFDR performance. Maxim's MAX19586 is the first device in a new family — higher-speed versions will soon follow, Maxim's Matta said.

All of these A/D converters are intended for use in demanding wideband communications applications, especially basestation receivers, as well as instrumentation and some other high-end type applications.

Cellular basestations have evolved from supporting voice only to supporting data and video also, which requires the receiver to have additional capacity. “The dB advantage we have will increase receiver sensitivity and enable our product to support multicarrier receivers,” Matta said.

Instrumentation applications also require strong dynamic performance to resolve small signals. “Our A/D converter will result in instruments that have more sensitivity, which will enable them to measure smaller signals,” Matta said.

It's also important to note that Maxim's MAX19586 includes an integrated buffer on the front end — which does effect power consumption (1.1 W). “Integrated buffers make it easier to drive the A/D converter depending on input frequency and the topology of the input network — but it results in additional power consumption,” Matta said.

On the other hand, if buffers are needed and they aren't included, then you have to figure out a way to drive the sampling converter yourself — with your own external buffer or transformer.

Most companies tend to offer either one version or the other — with or without buffers. However, Maxim is now considering offering one product family in both versions to customers, Matta said.

Linear Technology's LTC2208 includes two unique features that are said to simplify receiver design and boost system performance — an internal transparent dither circuit to improve the converter's SFDR response beyond 100 dBc, and a digital output randomizer to reduce unwanted tones caused by digital feedback.

LTC's A/D converter delivers 78 dB SNR and 100 dBc SFDR at 10 MHz.

Click here too see more details on LTC’s LTC2208 at eeProductCenter.

ADI ranks second in terms of speed at 100 Msamples/s (AD9446) with SNR of 76 dB and SFDR of 90 dBc at 10 MHz. The company also has an 80 Msamples/s A/D converter that achieves 82 dBfs SNR and 85 dBc SFDR.

Click here too see more details on ADI’s AD9446 at eeProductCenter.

Maxim's MAX19586 and Linear's LTC2208 are available in production quantities now. ADI is expected to offer production quantities next month.

Linear's LTC2208 comes in a 9mm x 9mm QFN and consumes 1,250 mW of power, compared to ADI's AD9446, which is packaged in a 16mm x 16mm TQFP and consumes 2,500 mW of power. Maxim's A/D converter is housed in an 8mm x 8mm, 56-pin TQFN and uses 1.1 W of power.

Linear Tech's LTC2208 and ADI's AD9446 are available in both low-voltage differential signaling (LVDS) and CMOS outputs. Maxim's MAX19586 offers CMOS outputs.

Linear also has a 16-bit, 105 Msamples/s (LTC2207) converter, with 78 dB SNR and 100 dBc SFDR at 10 MHz. It comes in a 7mm x 7mm QFN and consumes only 850 mW.

Pricing is $65.00 for LTC's 130 Msample/s device (LTC2208), $56.67 for its 105 Msamples/s version (LTC2207), $79.70 for ADI's AD9446 and $59.25 for Maxim's MAX19586 device — all in 1,000-piece quantities.

Analog Devices , 1-800-262-5643, www.analog.com.

Linear Technology , 1-800-454-6327, www.Linear.com.

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