Octal Receiver Lowers Ultrasound System Processing Overhead

Author: 
Bob Michaels
An eight-channel ultrasound receiver from Analog Devices Inc. minimizes ultrasound-system data bandwidth, power consumption, and system costs.

The medical device sector is no stranger to the increasing clamor for low-power, low-overhead equipment. In the ultrasound equipment market, for example, manufacturers are facing heightened pressure to develop low-bandwidth systems. Helping medical device manufacturers to meet this goal, Analog Devices Inc. (Norwood, MA) has introduced the AD9670, the industry’s first octal ultrasound receiver featuring digital demodulation and decimation processing capability.

“In the low-end and mid-range ultrasound market, a current trend is to build portable, small, and cost-effective systems that require low-power operation,” remarks Scott Pavlik, worldwide strategic marketing manager at Analog Devices. “In the high-end and premium areas, the trend is toward real-time 4-D imaging with higher volume rates, requiring simultaneous acquisition of multiple receive beams.” In both cases, manufacturers are challenged to reduce their systems’ data and computational rate in order to decrease power consumption and system size or to create a more computationally efficient system.

The AD9670 accomplishes these goals by reducing the data rate between the analog-to-digital converter (ADC) and the beam-forming circuits and by decreasing the required computation within the beam former, according to Pavlik. It also supports an ADC sampling rate of up to 125 million samples per second, post-ADC digital processing, and an output sampling rate of up to 80 million samples per second.

Key to minimizing ultrasound system overhead is the chip’s digital demodulation and decimation processing capability, Pavlik says. These features, he adds, make it possible to condition eight channels of data from radio frequency to a baseband frequency, reducing the processing load on the system’s field-programmable gate array (FPGA) by at least 50% compared with other receivers. Moreover, the chip’s integrated digital I/Q demodulator, programmable-oscillator, and 16-tap finite-impulse response decimation reduce the FPGA’s data bandwidth requirements.

“Nowadays, high-frequency ultrasound applications are shifting from the small-animal preclinical imaging field to human clinical imaging,” Pavlik says. However, powering high-frequency probes in ultrasound systems can require larger-bandwidth electronics, which is challenging and costly. The AD9670 removes the high-frequency carrier signal while maintaining the ultrasound signal bandwidth. It also minimizes the bandwidth and data rate demands on the beam-forming hardware. “The reduced data bandwidth,” Pavlik adds, “requires less processing overhead, reducing the size, cost, and power in the beam-forming circuits.”