Pharmaceutical & medical


Figure 2. An AD9106 functional block diagram.


that are in the 1 MHz to 40 MHz range, with external imaging machines typically using frequencies of 1 MHz to 15 MHz, while intravenous cardiovascular machines use as high as 40 MHz. Moreover, the AD9106 is highly integrated and has an on- chip pattern memory for complex waveform generation and a direct digital synthesizer


(DDS) with a 24-bit tuning word allowing 10.8 Hz/LSB frequency resolution. It is also highly programmable because pattern period, start delays, gain, and offset can be independently varied for each of the four DAC channels. In addition, it is low power (dissipating 78.8 mW/channel, 315.25mW total, at 3.3 V, 4 mA output, and


180 MSPS), which is an important consideration for large multichannel systems like an ultrasound machine.


Figure 3. A medical ultrasound front-end signal chain. Instrumentation Monthly June 2024


IMPROVING ACCURACY AND IMAGE RESOLUTION OF ULTRASOUND DEVICES Cart-based ultrasound systems are superior to handheld devices in terms of image quality or resolution mainly because of the big difference in the number of channels. Channel count, however, may vary from manufacturer to manufacturer. Since cost and power consumption are significant considerations in a large system such as the ultrasound machine, some techniques are used to minimise both factors. In a typical ultrasound signal chain in Figure 3, determining the number of channels is straightforward if we consider that there is one receiver path (integrated analog front end) for every transmitter path (DAC + high voltage amplifier), which drives one element in the array of transducers at the probe tip. With this assumption, we can say that number of channels in an ultrasound system can range from 16 to 256. The number of channels in


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