How to deal with medical electronic equipment design challenges?

Medical electronic devices from weak and complex body signals in collecting valid information, and on the basis of this information to monitor, display, and the diagnosis of disease, while avoiding medical electronic devices causing damage to the human body, the technical staff in the development of medical electronics equipment faced many challenges.

Recently, the 2008 China International Medical Electronics Assembly (CMET2008) was held in Shenzhen, from scientific research institutions, and medical electronics TI, ADI, Xilinx, Altera, Actel, NI, and other international semiconductor vendor experts delivered a fantastic keynote and with many participating medical electronic Enterprise technician, medical electronics trends and increasingly complex design challenges for Exchange and discussion.

Large medical electronic devices used for semiconductor devices

Shenzhen Siemens El dit NI magnetic resonance company into Dr. "large medical equipment in electronic technology," keynote speech that large medical equipment mainly used for the diagnosis and treatment, and civilian or portable medical electronic devices development there are many different considerations.

For example in magnetic resonance imaging (MRI) system, generally using high-speed FPGA for sequential control, data transmission, and high-performance DSP is used for real-time security monitoring. Development of large medical equipment are rarely purchase devices from the market, but with the development of semiconductor suppliers, special-purpose device for large-scale development of medical electronics equipment and semiconductor vendors compare long-term relations of cooperation. The medical equipment of non-real-time data needs bus protocol control, Siemens, GE, Philips, large selection of medical equipment have CAN-bus, while using Ethernet Powerlink (EPL) has gradually become a trend, but the bus is not suitable for such as ECG, biochemical Analyzer uses this type of equipment. In addition, NI, also to those who intend to develop and magnetic resonance imaging devices supporting the use of test equipment business proposal, you must ensure that ancillary instruments are completely non-magnetic, otherwise it will cause the supporting apparatus and magnetic resonance imaging devices interfere with each other, so there is this program the best enterprise is to find magnetic resonance manufacturers.

Low power: portable medical equipment demand significantly

From different semiconductor vendor experts speech found that providing longer battery life, lower power consumption become portable medical equipment with common characteristics of semiconductor devices, and high-performance, highly integrated, portable medical devices use analog device's main features.

Figure 1: SRAM in soft errors and error fixing.

Figure 2: fixed error on SRAM FPGA logic has serious implications.

Actel Asia Pacific Technical Manager wearing Meng-lin recommended choice for medical device design FPGA to the reliability, the highest consideration.

Because SRAM FPGA to achieve ultra-low power work usually requires the device to standby and shut off the power source, in hibernation before will register state SRAM to non-volatile memory, which makes the design of FPGA on SRAM and cost a great deal of influence. (See Figure 1, 2) Actel low power FPGA using Flash Freeze technology reduce power consumption, support this technology, the device simply 1us can access low-power mode. The Flash Freeze process of FPGA devices provide low power characteristics and makes the contents of a register is maintained, so Flash FPGA has SRAM technology and fuse technology advantages of FPGA and could also be "-error". Dai Meng-lin stressed the Actel's proASIC3L family of devices is a real single chip Flash GPGA, than those who merely SRAM FPGA and Flash blend package FPGA devices with higher reliability and lower costs.

At this Conference, portable ultrasound imaging system to become a semiconductor vendor mentioned most medical electronics design.

Latest ultrasound imaging system using digital processing of signal chain, the higher the sampling frequency and direction of portable direction. In these new ultrasound system needs to display 3D and even 4D high quality color images. With the ultrasonic system design of complex, how to deal with the modern ultrasound imaging design challenges?, two large FPGA Xilinx and Altera recommend ultrasound beam generator (Beam Former) design using FPGA with DSP performance.

Figure 3: Xilinx's high-performance digital beam generator program.

Xilinx Asia Pacific DSP product and solutions marketing business senior manager Lin Hong SEO represents a portable ultrasound system trend is a growing number of data need to be processed more quickly, so the ultrasonic imaging system of beam generator will require greater use of programmable, high-performance DSP platform.

Xilinx's low-power FPGA provides by using DSP48 Slice full spectrum of high-performance FIR filters, FFT algorithm even floating-point operations, while also reducing costs.

Figure 4: Altera devices in the application of ultrasonic systems.

With the need to increase the number of probes, beam generator in a corresponding increase in the number of channels, it means more DSP features and more high-speed serial interface, and PCIe interface and new DDR2/DDR3 will also be new portable ultrasound system.

Altera senior technical marketing engineer Cho Min pointed out that, in the ultrasonic system design which uses high-speed Stratix III FPGA can cope with the high-performance beam generator by these challenges, because Stratix III device has a large number of DSP module implementation of filtering and weighted function and supports multiple channels at the same time, or only support DDR3 'sFPGA; at the same time as adopting programmable power technologies, optional core voltage and optimization of chip technology, Stratix III device power consumption is significantly reduced, thus becoming the industry's lowest power consumption of high-performance FPGA.

ADI medical device product manager Paul Errico said CW Doppler ultrasound system image quality requires constantly improved, therefore the design process should adopt high-performance analog devices, portable ultrasound system selection of highly integrated analog devices also allows lower overall cost.

Paul Errico in the General Assembly introduced the ADI for CW Doppler processing introduced the eight-channel high performance analog front-end chip AD9271, 4 I/Q demodulator AD8339 and ultra-low power 16-bit ADC AD7980. Of these, AD9271 integrated LNA, VGA and 12-bit pipelined ADC, not only can improve portable medical equipment image quality, smaller chip area and low-cost advantages, but also improve the battery life and reliability.

Figure 6: bipolar process and CMOS process on ultrasonic system front-end device parameters of control.

Coincidentally, TI in the General Assembly also introduced a highly integrated 8 channel analog front end AFE5805 analog front-end, which is to determine the image quality and overall system performance is critical, however, that a low-power analog front ends is in a package in the integrated LNA, VCA and ADC.

TI analog signal chain applications engineer Chen Hong sang at the Conference stressed that, in the face of CW Doppler ultrasound system of noise, bandwidth and space, and other design challenges, using bipolar process and CMOS technology to different functional modules of the parameters have different effects (see Figure 6), so the engineers to focus on analog front end function module technology.