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Combining a 0.35-micron biCMOS process with improved circuit design and optimal layout and simulation techniques, Analog Devices Inc. has launched two high-performance, high-resolution analog-to-digital converters (ADCs) with unprecedented signal-to-noise ratio (SNR) and spurious-free dynamic range (SFDR) performance at faster sampling rates. While the 16-bit part delivers 100 megasamples per second (Msps) data rates, the 14-bit part boasts 125 Msps sampling rate.

Together, the reduced noise and 16-bit resolution of the AD9446 enables developers of instrumentation and automated test and measurement equipment, data acquisition systems, medical imaging devices and advanced military/aerospace communication subsystems to build more performance overhead into their designs by capturing a better representation of the input signal using fewer samples. Likewise, the 14-bit AD9445 is optimized for multicarrier, multimode receivers such as those found in next-generation cellular infrastructure equipment. The device's high resolution and outstanding performance also make it suitable for antenna array positioning, power amplifier linearization, broadband wireless, radar and infrared imaging, medical imaging, communications instrumentation, and software-defined and cognitive radios.

As part of a family of high-speed converters optimized to deliver higher sample rates and improved dynamic performance at competitive prices, the 16-bit AD9446 achieves a 10x increase in sample rates over other ADCs in its class while offering 90 dBc SFDR and 80 dBfs SNR at baseband — a full 6 dB better than the SNR achieved by the closest competing ADC, claims ADI. The AD9446 is available in an 80 Msps speed-grade option that also achieves industry-leading 85 dBc SFDR, while improving the SNR by another 2 dB to 82 dBfs SNR.

For high-performance test and measurement applications that use digital time sampling for frequency and time-domain analysis, the AD9446 significantly lowers aperture jitter to just 60 fs (femto seconds), compared to the 250 fs to 300 fs range of competing ADCs.

“Today's industrial equipment manufacturers are under constant pressure to scale the performance of their products without introducing new sources of signal noise,” said John Hussey, vice president of the high-speed converter group at Analog Devices. “In the case of advanced test equipment, for example, designers are on the lookout for ways to improve noise while maintaining a wide enough performance margin to ensure the reliable, repeatable testing of high-performance components, boards and systems. To build equipment capable of accurate testing and rapid debugs, these manufacturers need the resolution, speed and low noise characteristics that are enabled by the AD9446.”

In addition to delivering the industry's best 16-bit SFDR and SNR at baseband, the AD9446 is accurate and features a typical 16-bit differential non-linearity (DNL) of ±0.5 LSB and a typical16-bit integral non-linearity (INL) of ±3 LSB. Like other members of this family of high-speed ADCs, the new AD9446 features parallel low-voltage differential signaling (LVDS) outputs, including an output clock, which simplifies the interface to digital processing components and reduces the potential for digital noise coupling back into the ADC core (Figure 1). It requires 3.3 V and 5 V for operation. Typical power dissipation is 2.5 W at 100 Msps conversion speed.

According to ADI, the AD9445 is the first 14-bit, 125 Msps ADC to achieve an SFDR above 80 dBc and an SNR of 72.5 dBfs at input frequencies up to 300 MHz, better than competing solutions by a full 10 dB and 4 dB, respectively (Figure 2). A converter with high SFDR can capture weak signals in the frequency band of interest, despite the presence of strong, interfering signals. The industry-leading SNR characteristics of the AD9445 enable wireless infrastructure equipment designers to improve cellular base station receivers by offering lower overall system noise at higher intermediate frequencies, which translates to expanded cellular coverage and fewer dropped calls. Furthermore, the combination of high input frequency and high sampling rate eliminates a frequency downconversion step before the ADC, thereby easing the analog filtering burden. Both of these elements offer significant cost savings to the wireless system designer, said the supplier.

“The 14-bit AD9445 offers unparalleled SFDR and aperture jitter to expand the dynamic range of wireless base station receivers, while improving quality of service and lowering component count and cost,” said Ahmed M A. Ali, senior design engineer with ADI's high-speed converter group. The AD9445 also achieves an aperture jitter of 60 fs compared to the 250 fs to 300 fs aperture jitter of competing ADCs, which is critical to maintaining SNR at high input frequencies. Aperture jitter is the sample-to-sample variation in aperture delay and a major contributor to overall system signal degradation.

In addition to delivering greater than 80 dBc SFDR at a 300 MHz input frequency and 85 dBc SFDR at 225 MHz, the AD9445 provides high DC accuracy, with typical differential non-linearity (DNL) of ±0.2LSB and integral non-linearity (INL) of ±1.0 LSB. The ADC also features a flexible input range up to 3.2 Vp-p, allowing the user to achieve SNR performance as high as 78 dBfs, a full 6 dB better than any ADC of this class, while maintaining the state-of-the-art SFDR and IF sampling performance. The AD9445 also has an on-chip reference and track-and-hold, and parallel LVDS outputs to ease the interface to digital downconverters. The high-speed 14-bit ADC uses 3.3 V and 5 V supplies for operation. It offers 2.2 W (typical) power dissipation at maximum sampling speed.

The 14-bit AD9445 and 16-bit AD9446 are sampling with production slated for the end of the third quarter. Both the new high-performance ADCs come in Pb-free 100-lead TQFP/EP (thin quad flat pack/ exposed paddle) packages. Pricing for the AD9445-125 and AD9445-105 is $59.50 and $49.30, respectively, in 1000-unit quantities. In similar quantities, the AD9446-100 and AD9446-80 are priced at $79.90 and $72.25 each. The devices are supported by two evaluation boards and a behavioral model that can be used with Analog Devices' ADIsimADC modeling software.

Analog Devices Inc.
804 Woburn St.
Wilmington, MA 01887
(800) 262-5643
www.analog.com