MEDICAL EQUIPMENT & DEVICES ANALOG DEVICES
artifacts in the frequency-encode direction. For fast scan acquisition times, the compressed sensing technique based on undersampling is applied.
ULTRA-SONOGRAPHY Ultra-sonography or medical ultrasound is based on a physical principle different from all other imaging modalities discussed in this article. It utilises pulses of acoustic waves in the frequency range from 1MHz to 18MHz. These waves screen the internal body intensity. These echoes are acquired and displayed in real-time as a sonogram that may contain different types of information, including the acoustic or its stiffness.
ultrasound front end shown in Figure 5 is represented by an integrated multichannel analogue ADC, and demodulators. One of the most important requirements imposed on the AFE is the dynamic range. Depending on the imaging mode, this requirement can demand 70dB to 160dB to distinguish between probe and body tissue movements. Therefore an ADC must provide high resolution, a high sampling rate, and low total harmonic distortion (THD) to Low power dissipation is another important requirement dictated by the high channel density of the ultrasound front end.
CONCLUSION
Medical imaging imposes most demanding requirements on the electronic design. Low power, low noise, high dynamic range, and high resolution performance at low cost and in a the requirements of the modern medical imaging
Figure 4: MRI super-heterodyne receiver signal chain
systems discussed in this article. Here is a list of products ideal for the various medical imaging modalities mentioned in this article. ADAS1256: This highly integrated analogue front end incorporates 256 channels with low noise samplers that are multiplexed into a high speed, 16- bit ADC.
For discrete DR systems, the 18-bit PulSAR
ADC AD7960 offers 99dB of SNR and a 5MSPS sampling rate to deliver unmatched performance to meet requirements for the highest dynamic range both in noise and in linearity. The 16-bit, dual-channel AD9269 and 14-bit, 16-channel AD9249 pipeline ADCs offer sampling rates of up to 80MSPS and 65MSPS, respectively, to enable ADAS1135 and ADAS1134: These highly
integrated 256- and 128-channel data acquisition systems are comprised of low noise, low power, low input current integrators, simultaneous sample-and-hold devices, and two high speed
resolution of up to 24 bits with excellent linearity performance to maximise image quality for CT applications. AD9228, AD9637, AD9219, and AD9212: These 12- and 10-bit multichannel ADCs with sampling rates from 40MSPS to 80MSPS are optimised for outstanding dynamic performance and low power to meet PET requirements. AD9656: This 16-bit quad pipeline ADC offers a
conversion rate up to 125MSPS and is optimised for outstanding dynamic and low power performance for conventional and direct digital conversion MRI system architectures. AD9671: This 8-channel integrated receiver front end is designed for low cost and low power medical ultrasound applications featuring a 14- bit ADC with up to 125MSPS. Each channel is optimised for a high dynamic performance of 160dBFS/Hz and low power of 62.5mW in continuous wave mode for applications where a
Figure 5: Medical ultrasound front-end signal chain 22 October 2024 Irish Manufacturing
www.irish-manufacturing.com
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