Electronic Design

Ultrasound Reference Design Propels Medical Imaging Applications

When Samplify Systems introduced its SAM1600 family of analog-to-digital converters (ADCs) earlier this year, the medical ultrasound community took notice (see “Electronics Helps Foster Decentralized Healthcare”). These devices offered high performance in a small package combined with low power dissipation.

According to Samplify, these ADCs were the first in the industry to include integrated signal compression, providing the lowest power consumption per channel in the complete receive chain, without any compromise in performance. Besides medical applications, SAM1600s also are used in high-channel-density ultrasound radar/sonar, Long-Term Evolution (LTE) and WiMAX communications infrastructure systems, and automatic test equipment (ATE) applications.

Now, Samplify is offering a 32-channel reference design for ultrasound analog front ends in medical applications like imaging for pre-natal care, mammography, and cardiac blood flow studies (Fig. 1). “There are a lot of esoteric design issues for an OEM to verify that a chip set can work properly for an ultrasound application,” said David Kriendler, director of marketing. “This is why we introduced the reference design, which demonstrates that our product can deliver highquality performance at low-power levels.”

BY THE NUMBERS
Samplify’s family of 16-channel, 12-bit, 65-Msample/s ADC ICs integrates data-compression technology. It also boasts industry-leading power consumption in a 16-channel, 12-bit device of just 44 mW per channel. Performance is further enhanced by the integration of Samplify’s patented Prism datacompression technology, which reduces the number of low-voltage differential signaling (LVDS) I/O pairs, and thereby the power they consume, by up to 75%.

“Not only have we built a world-class data converter with twice the channel density and nearly half the power of competing solutions, but we have also integrated a sophisticated digital back end on the same die, improving I/O efficiency without degrading the analog performance of the part,” said Tom Sparkman, Samplify CEO.

The family includes the 16-channel SAM1610, the eight-channel SAM1605, and the 16-channel SAM1600, which enable the design of systems typically a third smaller than designs using conventional ADCs. The SAM1610 and SAM1600 feature 16 truly independent ADC channels, keeping crosstalk below the noise floor of the ADC. In contrast, the signal-tonoise ratio (SNR) performance of pseudo-16-channel devices, which time-share an ADC across two analog input channels, is limited by crosstalk. The products deliver a 68.5-dB SNR.

The Prism compression engine and port concentration technology reduce the number of LVDS outputs from 16 to as few as four in some applications. For systems not yet ready to exploit the benefits of compression, Samplify offers the SAM1600 in a traditional ADC configuration, allowing designers to take full advantage of the SAM1600’s higher channel density and lower power. The SAM1600 can also be configured as two independent octal ADCs with separate frame and clock outputs to maintain compatibility with legacy FPGA or ASIC beam-forming designs.

Performance also includes low latency with packet sizes as low as 96 samples and 800-Mbit/s serial LVDS outputs. The use of port concentration allows a 25% reduction in LVDS pairs at 50 Msamples/s and a 65% reduction of LVDS pairs with a 3:1 compression ratio. For a 256-channel console machine, a 75% reduction in LVDS pairs translates to 384 fewer FPGA pins and board traces between the SAM1610 and beam-former FPGAs, reducing power consumption, board space, and backplane complexity while allowing the use of fewer and/or cheaper FPGAs.

POWERFUL REFERENCE DESIGN
The 32-channel reference design is housed on a small printed-circuit board (PCB) footprint of 63 by 300 mm (2.5 by 1.2 in.). The board houses a probe connector input, four Maxim Integrated Circuits MAX2078 variable-gain/low-noise amplifiers (VGAs/LNAs), a pair of SAM 1600s, an output connector to FPGA circuitry, a reference, a clock, and a power supply (Fig. 2). Full design files for Orcad schematics and Allegro layouts are provided.

“Our low-power designs allow us to serve the portable and hand-carried ultrasound machine market,” said Kriendler. Samplify has orders from five of the top Chinese medical equipment suppliers. Also, the Chinese government has allocated $120 billion for medical equipment, much of it for ultrasound imaging equipment.

Packaged in a 12- by 12-mm, 196-ball ball grid array (BGA), samples are available now from Samplify or its distribution partners. Pricing for the SAM1610, SAM1605, and SAM1600 is $79.00, $39.50, and $64.00 in 1000-unit quantities, respectively. Customers using any SAM1600 family devices receive a royalty-free license to Samplify’s Prism decompression FPGA IP or software. A complete ADC evaluation board with data analysis software is also available now for $1995.00.

TAGS: Medical
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