Advanced ultrasound equipment must process signals with very high dynamic range to account for the variability in tissue and bone density, fluid viscosity, and the rate of fluid movement in the body. Furthermore, medical equipment designers need increasingly higher channel densities, which require hundreds of data converters and amplifiers per system, to enable the ultrasound AFE to render an accurate, high quality image.
Designers must address two major challenges: the need to drive data converters the channel density of their systems while shrinking power and package size.
Leveraging ADI's system-level signal chain and medical applications expertise, the components highlighted in the signal chain below, while available separately, together provide a complete, optimized AFE. This total solution not only increases dynamic range and image resolution in ultrasound equipment, but reduces package size, per-channel power consumption, and BOM costs. The quad VGA and 10-bit and 12-bit quad ADCs also feature serial, low voltage differential signaling (LVDS) data outputs that simplify board layout and further enhance image quality by enabling more data conversion paths to be routed within a given printed circuit board area.
The AD8334 quad variable gain amplifier (VGA) achieves a 101 dB signal-to-noise ratio (SNR) at 5 MHz-2.7 dB more than the nearest SNR of the closest competing VGA. The AD8334 uses 20% less area per channel, reduces per-channel power consumption by 20%, and cuts per-channel costs by 10% than that of other devices. The AD8334 also features an input-noise voltage level of only 0.74 nV/√Hz. Overload protection shields the device from ultrasound near-field signals and a selectable output clamping feature allows the VGA to protect the ADCs from signal saturation. It is available in a 64-lead LFCSP.
The 12-bit AD9228 quad ADC provides an ideal match for the AD8334 VGA. It is available in both 40 MSPS and 65 MSPS speed grades and achieves a 70 dB SNR and 82 dB SFDR. The AD9228 consumes half the board space and achieves more than 20% reduction in per-channel power consumption relative to other ADCs. The device also features a programmable clock and data alignment and allows for digital test pattern generation by using a serial port interface (SPI) that improves the ability of designers to control and synchronize output data. The AD9228 is available in a 48-lead LFCSP.