Chip enables image quality in portable ultrasound

Chip enables image quality in portable ultrasound

Analog Devices won a 2007 Product of the Year award for its AD9271 analog front end. We recently spoke with Corey Petersen, the lead design engineer, about the product’s development.

The need

The push for portable medical products has driven development of highly integrated, application-specific IC products. ADI’s experience in bipolar VGAs and CMOS ADCs provided the design team with a valuable understanding of the ultrasound market and its application-specific requirements. We developed an integrated ultrasound channel to gain efficiencies from focusing on key application requirements and traded off non-critical constraints of general-purpose products. An optimized and integrated design provided reductions in cost, power and size. This enabled a new generation of portable ultrasound products and made possible handheld systems not otherwise practical.

Even for an ultrasound product, flexibility is important to meet the performance and feature requirements of a broad range of end-market targets. For example, ultrasound systems may be battery operated or line powered. While at a high level all end-products may have similar architectures, tradeoffs and priorities vary from one ultrasound manufacturer to another and within these companies from one product line to another. While no one product can cover the full-range of ultrasound end-products, the AD9271 is the first in a family of products with user-programmable flexibility that addresses the requirements of portable-ultrasound applications.

Design challenges/obstacles

Our primary goal was to integrate the ultrasound receive channel in order to reduce system board space, power, and cost. We chose CMOS technology because it is cost-efficient and allows for the addition of user-programmable features.

Our biggest technical challenge was integrating the ADC with the low-noise VGA front-end. Both ADI insiders and our customers were skeptical about the feasibility of isolating the digital backend from the sensitive low-noise input in a monolithic product. We had experience in building wireless RF-to-bits system products and successfully applied the lessons learned there to the AD9271. Hitting the low-noise requirements was challenging in CMOS and required careful optimization of noise and power.

Beyond the design challenge, there were significant challenges preparing this product for manufacturing. Testing a chip with a high-input dynamic range, high gain and with high -speed digital outputs in a production environment challenged the test and product engineers.

Team

In developing the AD9271 we utilized a variety of technologies. As such, we collaborated with other ADI divisions to share design experience, application experience, and customer connections. Field teams and product line collaborated to define the product features and performance targets. Input from the field and customer connections were key in understanding the direction the market was taking. Customer system engineers who were using our existing VGA products were willing to critique our new product concepts and give input on features and performance targets.

Was there an unexpected event that happened?

Leveraging the design experience and applications understanding gained on the previous VGA products was important.

Considering the technical challenges, product development was relatively smooth. From the development team’s perspective, if anything unexpected occurred, it was the amount of interest that the product has generated from customers and even the competition.

Christina Nickolas