Eight channel chipset should enable high quality portable ultrasound

Comprising an analogue front end (afe), transmit/receive switch, transmit pulser and configurable transmit beamformer, the chipset allows the development of 128 channel portable ultrasound systems with enhanced image quality and diagnostics in a small footprint. "Previously, this level of ultrasound imaging quality was only attainable with large cart based consoles," said Dr Norbert Gaus, chief executive of Siemens Healthcare's clinical products division. "National Semiconductor has significantly raised the bar in terms of imaging performance and low power consumption for portable ultrasound systems." The four elements are: the LM96511 analogue front end; the LM96530 transmit/receive switch; the LM96550 transmit pulser; and the LM96570 transmit beamformer. The eight channel LM96511 features low noise amplifiers, digital variable gain amps (vga), 12bit a/d converters, LVDS data outputs and eight demodulators for CW Doppler beamforming. With a B mode power consumption of 110mW per channel, the device has a channel to channel gain matching figure of ±0.06dB. Suresh Ram, National Semiconductor's director, medical key market segment, explained the benefit of the digital vga. "If a doctor is looking at the liver, the blood flow is low and the blood vessels are relatively deep. This means the tones can be difficult to see with analogue vgas because noise is coupled back into the image. But this doesn't happen digital vgas and the benefits translate back into the frequency domain." The LM96530 contains eight transmit/receive switches with integrated clamping diodes and offers an individual channel shut-off capability, while the LM96550 contains eight pulsers with a damper circuit that generates ±50V bipolar pulses with peak currents up to 2A and pulse rates up to 20MHz. Finally, the LM96570 is said to provide an order of magnitude improvement in jitter performance improvement over beamforming traditionally done in fpgas. The 25ps peak to peak figure is said to enable much higher resolution imaging in B-mode and low blood velocity measurements.